I just took the Physics GRE. I was fairly well prepared, studying wise, but didn't do as well as I was aiming to, largely do to time constraints, and I wasn't moving as fast as desired. Still think I did "ok" but as my purpose was to do very well or even excellently, well you know... I got to wondering about how many forms there are for a particular GRE exam, and how they pick the questions for these forms. There are some general guidelines as to the percentage of questions from certain topics to expect. But my sense on my last exam was that these proportions varied quite substantially from what is written in the front of the test book. I saw a little variance in the practice books, but on my last exam I actually found it a little weird as to the extent to which certain topics appeared and others didn't. Do they pick these questions at random, or is their a rhyme and a reason to how they are divided up? For instance on a particular exam one could find that there were actually more like 30 percent classical mechanics problems, and relatively few E&M problems, and very few QM problems, as opposed to the average proportions, which some people could find good, but others might think undesireable because typically the QM problems and EM problems could be attacked more quickly if you are proficient there, than some of the CM problems, not that that was my particular case, but wanted to provide hypothetical example. Any thoughts?