Well, the book, HF EJB, indicates at several pages that things need to be memorized and that the exam tries to confuse you in its questions and if that is true are there so many small details so learn and memorize. But I don�t know how sadistic, as one of my colleagues expressed it, the questions is before I have been at the real exam. When the examiner is a computer are there no chance to get any kind "well, he have at least understood it" points. There is just right or wrong.
SCJP that I did three years ago were somewhat "sadistic" but code syntax scares me less than subtle semantic that I feel is harder to memorize. And that makes me a bit frustrated
But I think you are somewhat right, just memorizing is not the way to go. I try myself as often as possible to find out why the different rules and semantic works as it does because it is easier to remember things you really understand why they are as they are. And yes, I also think that the diagrams is important because pictures sometimes are easier to remember than just text. And I have tried to create a little
test program for most of the things, the different bean types, included in the exam to have something concrete and working to refer to when I try to remember how it works. This is the way I try to help myself memorize.