That depends on what your program is like. Some programs use the SAE for what it is intended (as means for residents to find out what areas of PMR they're weak at), while other programs use the results of the SAE as an advancement tool (u must get a certain score in order to advance to the next PGY; or if u score below a certain score, u must get additional tutoring from faculty).
So if you go to one of the later programs, I'd suggest becoming a member of the AAPM&R, then downloading all the old SAEs they have (2001-current) and learning by doing those questions. Otherwise, the "Physical Medicine and Rehabilitation Board Review" book is great...I'd just wait until the new edition comes out (supposedly this Fall, but they've been pushing it back for years).