Its a tough shelf exam. I just had it as my first rotation. With respect to the selection of questions on my particular shelf, pretest was really helpful. A few near identical questions. Ditto with AAFP. Actually I got a question about early feeding that im pretty sure was also on AAFP (if anyone remembers the answer let me know; it was about why you shouldn't intro solid foods early on in infancy)
I found casefiles to be absolutely garbage. The format is just not very high yield since its more so reading than questions and the reading is really low yield. If you like reading more than questions do this but i found swansons the best balance.
AAFP + Swansons + Pretest (the latter you can do in the days before the test, its very fast) should have you as covered as anyone can be.
Ill let you know how i ended up doing. I never finished all of swansons (just the adult and female health) and I still had 500 AAFP left. I did nearly all of pretest. I was fasting for ramadan at the time but really if I had just not bothered with casefiles and spent that time more wisely, i think i would have done much better.