For the same reason people spent money on the terrible Kaplan practice MCATs in undergrad: because doing the same questions (e.g. the AAMC practice exams for the MCAT) multiple times doesn't test your knowledge as much as it tests your memory for that specific question.
For the same reason people spent money on the terrible Kaplan practice MCATs in undergrad: because doing the same questions (e.g. the AAMC practice exams for the MCAT) multiple times doesn't test your knowledge as much as it tests your memory for that specific question.
UWorld is great. But some students feel like they are missing something if they don't do Kaplan too. I guess if money is not an issue than it doesn't matter. In any case, studies show higher scores on the USMLE correlate with number of questions completed. So either doing UWorld twice, or doing UWorld and Kaplan can only help you.