You are correct, this was the hardest test in basic sciences for me. In our class, the top scorers did all of BRS Physio and every single Kaplan Physio and Pathophys question in the last two weeks or so. One guy got a 99th percentile doing that, he was doing 120 questions a day and we had mandatory 8-5 classes everyday.
I felt like the key was just knowing physiology, so if someone had read the big Constanzo text throughout M1/M2, then read it again in the last few weeks and did brs physio plus just as many questions in general, they were in the best shape. I'm glad I didn't use up my Kaplan questions just for a shelf, but that was really effective for many people in my class as that is a very good physio heavy question bank.
If you are really pressed for time, just try to go through the physeo videos at double speed in a couple days and then just start doing 100's of questions (BRS, Guyton, qbanks)