Just wanted to post for future ABIM takers. This was my first time taking it. I scored horrendous on my in service exam. I think it was something like 30th percentile 1st yr, 20th 2nd year, and 6th percentile 3rd year. Ironically, my percentage correct was fairly steady throughout the 3 yrs, but the grading increased as you progressed from PGY 1 to PGY 3. I know, it was terrible. I never studied towards the ABIM during my residency, and used my time to pursue getting a competitive fellowship which I was successful. After early December (fellowship match results came out), I started studying for ABIM.
I bought the UWorld 1 yr subscription. First time through UWorld (took me around 6 months) off and on, on tutor mode, I scored I believe a 59% correct, which was a pretty good percentile actually (forgot what it was, like maybe 75th percentile). I read all the MKSAP books word for word, and did all the questions on MKSAP, and BB3. I would read MKSAP and MKSAP questions on random on the books (mark off which pages I read, and which questions I did). I did not keep track of my percentile on MKSAP, though I suspect it was probably around 70%, and much easier than UWorld.
After going through MKSAP, and UWorld, and BB3, this was around mid June. After this, I did not have much more time to study as I started fellowship in July and it was hectic from there on out. I decided to only focus on UWorld, and just redid UWorld, and from mid June to early August, I was able to go through about 75% of UWorld the 2nd time around, with my 2nd time around average close to 70% correct, which correlated to around i believe > 90th percentile.
Looking back, I felt UWorld was the best resource, the questions, and answers were very high yield. Thought the question difficulty on UWorld was much harder and indepth than the actual test and MKSAP, understanding the questions and the answers I felt was very high yield towards the real exam. I do not believe it replaces MKSAP, but they are very complimentary to it. This is all I used, and I passed doing this route. Classmates used Awesome review or medstudy, and they felt it helped, but I cannot comment as I did not use it. There is no one way of doing it, just wanted to share my way. Hope it helps for the future test takers.
Addendum: Just got my score report. Score 493, referece mean 468, passing score 370