The OBGYN shelf is pretty doable. Along with psych and maybe neuro, it's one of the few specialties where you can actually have a pretty decent handle on all the material tested on the shelf by the end of a clerkship. On medicine, surgery, peds, FM, and EM, you rely pretty heavily on connecting the dots based on basic principles and getting questions based on randomly remembering some detail from either the wards or a single question you did (maybe even as far back as M2/step 1 stuff). On OBGYN you can legitimately go through all major concepts 2-3 times prior to the shelf.
IMO, UWise was worthwhile. I didn't do the whole thing, but being split into topics was super helpful as that's just far more effective teaching for building a framework of understanding compared to randomly doing UWorld blocks. It's also fast. The explanations are concise and you can easily burn through 100+ questions on a day off. I did UWorld and about 1/2 of UWise and make ankis from incorrects or from concepts I didn't know as I was reading the question. I also did the Emma Holiday and Divine reviews the day before, which definitely got me 3-4 questions I otherwise wouldn't have on test day. Scored ~95th percentile.