for the 70’s I went through and used the review function mostly. As I came to sections I was less comfortable with, I would filter those out and spend a little bit more time on them. if there was a question I repeatedly got wrong I tried to find a way to memorize it (usually some of those one’s were pretty unique and I could come up with some sort of word association). Other questions I would just not worry about. 21 questions is a very generous amount to get wrong. sometimes you have to recognize your weaknesses accept them, and move on. The amount of information in those three sections alone is enough to drive you crazy and spending absurd amounts of hours on one section that you don’t have down 100% is even crazier. Good luck and remember to RTFQ, it’s so damn easy to get burned on a question that looks a lot like another!