MURNAGHAN, Circuit Judge:
Burgess is a Vietnam war veteran who suffered stressful experiences during his stay in that country, among them direct participation in the battle of the Plain of Reeds. Following his return to the United States and discharge from the Army, he was engaged, in May of 1981, in activities which led to a prosecution in the United States District Court for the Eastern District of Virginia on charges of (a) conspiracy to distribute cocaine,1 (b) distribution of cocaine,2 and (c) using a telephone to facilitate the distribution of cocaine.3
As the case evolved, performance by Burgess of the proscribed acts was not disputed.4 His brief on appeal candidly concedes that the facts establishing the offenses were uncontested by the defense, that a prima facie showing was made by the Government, and that: “The entire defense [1148]*1148rested upon whether or not Burgess was legally insane at the time of the offense.”
The defense asserted a Post Traumatic Stress Disorder (PTSD) allegedly activated by Burgess’ Vietnam experiences. Medical experts appeared for both parties. There was testimony which, if believed, established beyond a reasonable doubt that Burgess was not insane. The jury returned a verdict of guilty as to all three counts, and normally that should have concluded the matter.
Burgess contends, however, that, as the case was presented to the jury, he was mouse-trapped by the Government with the consequence that valuable testimony which would have materially strengthened his case was not introduced. As courts have had frequent occasion to observe, the question before us on appeal frequently boils down not to whether sufficient evidence of the commission of the crime charged was alleged and proven, but rather whether the accused’s constitutional rights to due process and especially to a fair trial were scrupulously protected.5 We address that issue here.
The claim of Burgess centers on a colloquy between counsel and Judge Williams which occurred immediately prior to the presentation of the defense’s case in chief. The colloquy commenced with a statement by one of the prosecutors questioning the relevance of certain evidence to which, in opening statement, defense counsel had alluded, specifically the experiencing by Burgess of the breaking up of his home. The position taken by the Government was that the evidence, while manifestly designed to evoke sympathy, was simply not probative as to the existence vel non of mental disease or defect. ,
There then evolved a brief exchange concerning the proper point in the trial at which other defense evidence should be offered.6 Defense counsel indicated that the Government was expected in its rebuttal case to adduce evidence that the insanity [1149]*1149defense was contrived, i.e., faked. Defense counsel pressed, in general terms and necessarily on an anticipatory basis, for rulings permitting, as part of the defense-in-chief, evidence described as going to show the genuineness of the PTSD insanity defense. The Government (also speaking, of necessity, in the abstract since the colloquy preceded the actual submission of any item of evidence on the insanity issue) objected to the introduction of such evidence as part of the defense’s case in chief, contending that an orderly and proper development would dictate the deferral of such testimony to surrebuttal.
The trial then resumed. Following completion of the Government’s rebuttal case, testimony proffered by the defense as surrebuttal was objected to by the Government and was in large measure, though not completely, excluded.
Obviously, if defense counsel was indeed led reasonably to rely on the Government’s contention that testimony should be reserved for surrebuttal and was then foreclosed from introducing the evidence on the grounds that it properly was part of the defense-in-chief, an injustice has occurred which would mandate reversal and remand for a new trial. However, the Government replies that its remarks at the time of the colloquy were only intended and properly only could be read to go to evidence which indeed was proper surrebuttal. So long as the discussion was purely in generalities, it remained for defense counsel correctly to assess whether each item the defense wanted to put in evidence after the Government rested its rebuttal case properly met the criteria for surrebuttal. Evidence which should have been put in as part of the case in chief, or which, being merely repetitive of other evidence already before the jury, would not be proper surrebuttal testimony, could not have its status changed merely by application of the label “Surrebuttal.” Defense counsel, the Government argues, had no reasonable basis for relying on the abstract statement of a prosecutor during the colloquy between court and counsel which indeed boils down simply to the truism: “Surrebuttal is surrebuttal.” The statement did not authorize the holding back of testimony which went to the issue of insanity itself rather than to the issue of whether there had been an effort to fake insanity.7
Since the discussion at the colloquy between court and counsel was couched in terms general in nature, without specifically identifying the testimony which the Government contended should not be offered by the defense until surrebuttal, it becomes our responsibility to look to the several items of proffered testimony to determine into which category each, in fact, fell. To the extent that an item was not proper surrebuttal but indeed belonged, if admissible at all, in the defense-in-chief, the Government’s position would be well taken.
In the colloquy between court and counsel Judge Williams, properly cautious, stated with respect to the Government’s premature claim of irrelevancy: “I can’t rule on it in any advisory way.” He went on to ob[1150]*1150serve that testimony about the defendant in normal stress situations could be counterproductive to the establishment of the PTSD defense.8 The court concluded: “I am sure that after the matter is looked at more maturely ... it will be tempered in such a way that.nothing objectionable will come out.”
The colloquy then moved on to the observation from the defense that the Government had stated its intention in rebuttal to present testimony that the whole PTSD defense was contrived. Defense counsel raised the question of whether it could introduce in its case-in-chief corroborative evidence that Burgess was not faking the defense. Without specifying what the testimony would be, defense counsel stated a wish to have the testimony in the case in chief so that the jury would know “this is not a game that is being played on them.”9 The Government noted that testimony to refute a claim of fakery would be more properly restricted to surrebuttal.10 The district judge sensibly responded by stating: “I will rule on those things when they come up.” 11
The defense’s case-in-chief consisted of the testimony of two medical experts. Dr. Sonnenberg testified to a wide range of circumstantial matters leading him to the conclusion that Burgess suffered from PTSD and opined that, as a result, Burgess was legally insane. Dr. Levin testified as to four objective psychological tests given by him to Burgess and expressed his conclusion that the results confirmed Dr. Sonnenberg’s diagnosis. In the course of his testimony, Sonnenberg explained that the information on which he relied came not from Burgess alone but in addition was confirmed from other “independent” sources, i.e., was not faked.
After the defense rested its case-in-chief, the Government, as part of its rebuttal, called McCoy, a personal acquaintance of Burgess. McCoy testified that Burgess himself had expressed disbelief in his own “Vietnam syndrome” defense and had stated that he would feign insanity at the trial. Commarato, a DEA agent, was called and stated his observation that Burgess’ behavior at the time of the offense was “very cool, calm, very cautious, typical of a dope dealer.” Also, the Government, as part of its rebuttal, submitted testimony of a medical expert, Dr. Pepper, who expressed the conclusion that the PTSD defense in gener[1151]*1151al was contrived, further concluding that Burgess was not suffering from PTSD.
Then the surrebuttal commenced. What happened reveals one of the difficulties flowing from the imprecise use of language.12 In the earlier colloquy, counsel for the defense may have sincerely believed that the evidence they now sought to introduce on surrebuttal was the testimony which the Government had argued should be reserved for surrebuttal and not introduced as part of the defense’s case-in-chief. However, that belief must have derived simply from defense counsel’s own estimate as to the surrebuttal character of the testimony. There is nothing to suggest that the Government took a surrebuttal stance with respect to any specific evidence, only to turn around and object successfully later on on the grounds that the evidence did not merit the description of surrebuttal but rather properly was material that should have been introduced as part of the defense-in-chief. We are unwilling to say that the Government must accept responsibility for a misunderstanding deriving from the imprecise use of legal terminology. It was not the fault of Government counsel that testimony not truly surrebuttal in character was intended to be encompassed in defense counsel’s statement that, to refute the charge of contrivance, which defendant expected would at a future time be injected into the case, he did want to get the testimony before the jury and intended to try to do so in the defense-in-chief. The trial judge very properly indicated that he would not rule in advance and left to counsel what was indeed counsel’s responsibility, namely, the decision as to when was an appropriate time for the testimony to be offered.
It becomes, therefore, necessary to consider the evidence of which Burgess contends he was wrongly deprived, to see to what extent, if any, he is on sound ground. There were four witnesses involved in the defense effort to construct a surrebuttal case. First, the defense produced a fellow soldier who had served in the same battle in Vietnam with Burgess. His testimony would have gone to establish the existence of the battle of the Plain of Reeds, one of the major stress factors which had been identified by Dr. Sonnenberg. However, the Government, as part of its efforts to establish fakery, had never suggested in any way that the battle had not taken place, with Burgess a participant, or that Burgess had not told Dr. Sonnenberg about it. Dr. Sonnenberg had in his direct testimony referred to the battle.13 It was well [1152]*1152within the discretion of the district judge, in our judgment, to exclude the testimony of the witness proffered in surrebuttal since it injected no new issue14 and would merely have been repetitive of the prior testimony of Dr. Sonnenberg.15
Most importantly, as the case had developed, the evidence which the trial judge did not admit at the late surrebuttal stage did not constitute material which the Government had opposed and had succeeded in excluding as part of the defense-in-chief. Nothing which had occurred at the colloquy, consequently, dictated that the testimony of the fellow soldier should have been allowed in surrebuttal.
A close personal friend of Burgess, Betsy Hatch, was then proffered to testify that the topic of Vietnam was off limits insofar as Burgess was concerned and that he never discussed it. Her testimony would also have described Burgess’ condition in May of 1981 and the dramatic deterioration in his condition following his mother’s funeral. Again, exclusion was based on the grounds that the testimony was merely repetitive.16
The purport of the testimony was once again to establish the existence of PTSD rather than to rebut a case of fakery. While the two concepts may on occasion tend to merge, we are satisfied that it fell within the trial judge’s discretion to exclude [1153]*1153the testimony, especially since it was already before the jury. Otherwise, expansive surrebuttal would contribute to the undue prolongation of cases and the reiteration several times over of the same evidence.17
Dr. Levin, one of the experts earlier called by Burgess, was also produced for surrebuttal purposes. He was put forward to testify that the defense was not, in his opinion, fabricated. Assuming that such a contradicting expression of expert opinion constituted surrebuttal testimony, nevertheless the district judge was justified in not permitting the testimony for the independent reason that it was merely repetitive of what had already been stated by Dr. Levin in the defense’s case-in-chief.18 Thus, had Dr. Levin been asked, during the defense case-in-chief, the very questions he was not permitted to answer on surrebuttal, a ruling excluding the testimony as repetitious would have been well within the trial judge’s discretion.
Repetitiveness is a justifiable basis for excluding evidence offered on surrebuttal even though it may otherwise be relevant.19
Finally, in the case of Dr. Sonnenberg, who was the last witness offered on surrebuttal, some questions were permitted to be asked and answered.20 However, the court [1154]*1154excluded an attempted reiteration of the testimony that materials other than what Burgess told Dr. Sonnenberg were significant and relied on by him in reaching his conclusion. Once more the testimony was simply repetitive.21 The evidence merely served to reemphasize the defense-in-chief rather than to contradict the Government’s rebuttal case.
Thus any error with respect to the timing of the attempts to introduce the evidence characterized by counsel for Burgess as “surrebuttal” must be laid to defense counsel and not to the court or to the prosecution. However, the statement that defense counsel may have erred in putting off until the defense’s surrebuttal case evidence not properly admissible at that late and quite tightly circumscribed stage of the case should not be deemed to amount to an expression that there may have been ineffective representation by counsel. In the first place, we are, for sound and obvious reasons, strongly disinclined to make such a judgment on direct appeal, when counsel has had no opportunity to speak to his side of the matter. See United States v. Lurz, 666 F.2d 69, 78 (4th Cir. 1981), cert. denied sub nom. Magill v. U. S., 455 U.S. 1005, 102 S.Ct. 1642, 71 L.Ed.2d 874; sub nom. Steedman v. U. S., -U.S. -, 102 S.Ct. 2966, 73 L.Ed.2d 1354 (1982).
In the second place, moreover, as a strategic matter, counsel may well have taken a calculated risk, hoping to succeed in a plausible (though ultimately, for reasons we have adduced, unsound) approach. He could well have viewed the prosecutor’s statement during the colloquy (“If that’s the case, then those witnesses are more appropriately called in surrebuttal.”) as manna from heaven or a life line thrown to a drowning man. Boldly seeking to expand the meaning of the observation of his opponent beyond its reasonable limits, defense counsel, had he succeeded, would have achieved the maximum effect in dissipating or obscuring the significance of the damaging testimony as to the contrived nature of the defense. On the other hand, were the testimony to have been offered and admitted where it properly belonged, that is before the Government’s rebuttal, as part of the defense’s case-in-chief, it could have been expected to have far less impact. The latest piece of evidence on the subject, being a direct quotation of Burgess himself that he was faking, was apt to be the most effective with the jury.
So counsel may well have been doing the very best by his client in making an attempt — albeit ultimately an unsuccessful attempt — to obtain a change in the customary order for the proper introduction of evidence.22 The game was probably well worth the candle, especially when it is taken into account that whatever evidence was lost was largely cumulative of other testimony which had previously been admitted.
[1155]*1155It should be borne in mind that prospects for achieving a successful defense were exceedingly remote. Commission of the acts constituting the substantive offenses, in counsel’s judgment, could not be refuted. Yet confession and avoidance provided little hope of an escape for Burgess from the rigors of the law. Alignment of the insanity defense with statements made by Burgess while the crimes were still in their evolutionary stage expressing comfort that he would be well prepared, if caught, to defend against criminal charges,23 would not be easy. The apparently antithetical nature of the positions, the innate improbability of coalescing a calculating cocaine pusher with someone who could not appreciate the criminality of his acts or conform his conduct to the requirements of law,24 could hardly be lost on the jury. Thus an extraordinary and unorthodox approach, even one with little chance of success in the presence of an astute trial judge and alert Government counsel, would have been understandable. Defense counsel may have perceived an opening for delaying or repeating the defense’s most effective testimony when the prosecutor, on the basis of a generality, arguably might be said to have called for postponement of much of defendant’s evidence to the surrebuttal phase.25
There are numerous other contentions raised by Burgess. First, Judge Williams, following a discussion with counsel prior to closing arguments of proposed jury instructions, determined sua sponte to add language to flesh out the discussed instructions. Without informing counsel prior to closing arguments, he inserted the following:
Bear in mind also, ladies and gentlemen, that experts, and particularly medical experts, are dependent upon information that they receive in taking a history from the patient. If the patient gives them false information in that history, the experts’ opinions and conclusions can be flawed because the material he had to work with was unreliable.
The case for the proposition that the charge was substantively in error is unpersuasive. “Garbage in, garbage out” is a concept not exclusively confined to computers. In light of the testimony, both of Dr. Sonnenberg and of Dr. Levin, that they relied on other materials and did not base their opinions solely on what Burgess had told them, the instruction was more apt to be harmful to the Government, whose expert had not testified as to independent verification on which to base his conclusions.
The only potentially troublesome point raised by the defense is the contention that the sua sponte and uncommunicated character of the instruction created error violating F.R.Crim.P. 30. The rule, dealing with jury instructions, permits any party to file written requests as to instructions. The court is then required to inform counsel of its proposed action upon the requests prior to closing arguments.26 An obvious short answer [1156]*1156could be that the instruction here dealt with was not the consequence of a request by either party, rendering F.R.Crim.P. 30 altogether inapplicable. However, the Seventh Circuit has expressed itself otherwise in United States v. Bass, 425 F.2d 161, 162-63 (7th Cir. 1970):
.. . [U]nder Rule 30 ... we think counsel should be informed of all instructions that will be given to the jury and to read Rule 30 as being applicable only to instructions proposed by counsel would emasculate its purpose which is in part to allow counsel, knowing the instructions to be given, to effectively argue his case to the jury.
We see no necessity for resolving a potentially extremely serious and far reaching question as to the proper interpretation of F.R.Crim.P. 30, since, even accepting the statement in Bass as good law,27 a remand would not be called for in the circumstances of the present case. For all the circuits which have dealt with the problem, including the Seventh Circuit which decided Bass, require a showing of prejudice. See, e.g., United States v. Lyles, 593 F.2d 182, 186 (2d Cir. 1979), cert. denied, 440 U.S. 972, 99 S.Ct. 1537, 59 L.Ed.2d 789 (1979), and sub nom. Johnson v. United States, 440 U.S. 975, 99 S.Ct. 1545, 59 L.Ed.2d 794 (1979), and sub nom. Holder v. United States, 444 U.S. 847, 100 S.Ct. 94, 62 L.Ed.2d 61 (1979); United States v. Newson, supra, at 983 (citing F.R.Crim.P. 52(a)).
We are satisfied that, even if Rule 30 requires that the court inform counsel of its sua sponte modification of the instructions prior to closing argument, there was no prejudice. Defense counsel was careful in closing argument to refer to the fact that there was independent confirmation of the facts which were relied on by defense experts to conclude that Burgess had suffered PTSD.28
Next we turn to the defense’s contention that it should have been allowed to employ for demonstrative purposes charts listing the diagnostic criteria for PTSD. The district judge was well within the scope of his discretion in ruling that visual aids were not to be used to conduct the examination, since the points could adequately be made simply by verbal testimony.29
[1157]*1157Again on the basis that verbalization was an adequate means for presenting a proposition, the judge, in the proper exercise of his discretion, refused to permit Dr. Sonnenberg to use a blackboard “to draw a diagram that will describe in metaphorical terms his [Burgess’] experience of guilt. I want to put on the blackboard a diagram that concerns his life history and the stages of guilt he was experiencing.”30
The defense further contends that there was error sufficient to require reversal in the district court’s ruling that the psychiatrists for both parties might remain in court despite the F.R.Evid. 615 provisions calling for exclusion of witnesses. Rule 615 permits an exception in the case of “a person whose presence is shown by a party to be essential to the presentation of the case.” It was the Government’s contention that its medical expert, Dr. Pepper, needed to be present. The court did not abuse its discretion, particularly since it evenhandedly afforded the same opportunity to the defense., See Morvant v. Construction Aggregates Corp., 570 F.2d 626, 629-30 (6th Cir. 1978), cert. dismissed, 439 U.S. 801, 99 S.Ct. 44, 58 L.Ed.2d 94 (1978). There it was held that:
[W]here a party seeks to except an expert witness from exclusion under Rule 615 on the basis that he needs to hear firsthand the testimony of the witnesses, the decision whether to permit him to remain is within the discretion of the trial judge and should not normally be disturbed on appeal.
The circumstances in the instant case were such that the ruling permitting the two medical experts for the defense, and the Government’s expert, to remain in the courtroom throughout was not an abuse of discretion. Written reports from the medical experts were delayed to the point that they were forthcoming from defendant only two days prior to commencement of the trial, and, from the Government, on the second and last day of trial. It was reasonable not to place the experts under such short time constraints for familiarizing themselves with each other’s findings by reading through reports, and, therefore, reasonable to permit all of them to appear in court.
It is unnecessary to decide whether the absence of any demonstrable prejudice flowing from the failure to exclude the Government’s medical expert would, in all events, eliminate the force of the contention. We have so ruled in a case where the record disclosed no prejudice to the defendants on trial. United States v. Harris, 409 F.2d 77, 81 (4th Cir. 1969), cert. denied, 396 U.S. 965, 90 S.Ct. 443, 24 L.Ed.2d 430 (1970). However the case antedated the effective date of the Federal Rules of Evidence. It is arguable that the specific language of F.R. Evid. 615 automatically mandates reversal whenever noncompliance with the rule is shown. See United States v. Warren, 550 F.2d 219, 227 (5th Cir. 1977), modified enbanc, 578 F.2d 1058, 1076 (5th Cir. 1978), cert. denied, 434 U.S. 1016, 98 S.Ct. 735, 54 L.Ed.2d 762 (1978). We need not, and do not, address that question.31
The defense further contended that a government participant in the trial who remained in the courtroom32 prejudiced the defense’s case by a statement in the pres[1158]*1158ence of the jury that Burgess “was about to turn on his crying act.” In the first place, there is no sufficient evidence that the statement was overheard by any juror. In the second place, the remark is no more than a repetition of the Government’s claim that the PTSD defense was contrived. The defense admitted that it could not prove prejudice and, that being the case, the district judge did not abuse his discretion in denying a new trial on those grounds.
Inasmuch as the defense concedes the occurrence of the substantive offenses, and indeed that was “never contested by Burgess,” we need not long delay over a supposedly undue restriction of impeachment of a primary Government witness to the substantive elements of the crime. There was no abuse of discretion. See United States v. Dominguez, 604 F.2d 304, 310 (4th Cir. 1979), cert. denied, 444 U.S. 1014, 100 S.Ct. 664, 62 L.Ed.2d 644 (1980) (“The scope of permissible impeachment of a witness in a criminal trial generally is committed to the sound discretion of the trial court.”). Furthermore, the district judge gave the defense the opportunity to ask the witness the desired question outside the presence of the jury, indicating that he would reconsider his ruling depending on what answer the .witness might give. That was an eminently reasonable procedure. Yet, defense counsel never followed up by requesting that the testimony be given outside the jury’s presence.
Finally, complaint is voiced about the fact that the trial judge leaned back in the course of closing argument, closing his eyes while he did so. The judge observed:
There is no question that I leaned back and I closed my eyes, but I wasn’t nodding at all, I was totally alert.
We know of no rule requiring the judge to refrain from closing his eyes, especially during closing argument of counsel. The argument, after all, was addressed to the jury who had the responsibility to weigh counsels’ comments in the course of its deliberations.
Finding no reversible error, we affirm the judgment below.
AFFIRMED.