I agree that agreeing to be questioned and then saying you don't recall endlessly is mostly absurd.

However, you know he has gone through hours of very recent prep with his defense lawyers about the specific questions he'll be asked by the team. So, it's not exactly fair to accuse him of having perfect recall for his defense lawyer's questions and not as much for the prosecution.

Surely the defense team would game theory the case and prepare for likely prosecution questions. Those are the hardest ones for which you need to prepare.

In that case you would remember.