It can be very powerful.
In my one experience on jury duty, we were the first jury in our area to be allowed to take notes during the trial. During voir dire, we all heard the questioning of all potential jurors, and we all heard the defense attorney ask each one if they would be willing to acquit when they proved a specific point. We heard him repeat it in the opening statement. We heard him hammer on it in his closing. In deliberations, the two people on the jury who had decided not to bother taking notes were totally convinced on the point by all that repetition, and the 10 of us who did take notes had to show them that the defense had never produced that promised evidence. (Amazingly, the totally incompetent prosecutor had not mentioned that in her own closing.)