Rx first to drive home the basics and get used to questions. Kaplan second to get used to nit picky details. Uworld last. I do not think its worth doing anything twice unless you've already finished all 3 banks and, even then, I would only suggest redoing the questions you missed. I think Uworld is over-hyped but I still think its slightly better than the others. The real test for me was not as purposefully tricky as Uworld or as detailed. I also highly recommend a spaced repetition program like firecracker or anki as your main foundation of studying...beginning early in MS2. (I got a 259 and this is what I did)