I used this book on amazon that was like $3-4 on Kindle. It was a simple 200-ish question Q&A. Went through it twice over the course of a few hours. Also our residency had stacks of old questions/tests to help residents quickly study for it (so we can moonlight!). Overkill? Probably, but honestly a solid day or two you should be good. You get immediate results once you finish.