Rx is really easy though. I can plow through 46 questions of Rx in like 15-20 minutes (medium/hard questions only, organized by system), and score in the 70-80% range without any prep other than classes (eg no looking at First Aid). Most of the questions are 1-step or 2-step reasoning, with few distractors and easy to eliminate answers.
In contrast, Uworld takes me closer to a minute a question and really requires some thinking to link the different disciples together. There are less straight recall questions and more thinking questions involved. So you really can't compare Uworld and Rx; they serve two entirely different purposes. Rx is First Aid in qbank form and not much more than that. Uworld is a full integration of concepts that requires multi-level recall in order to do well.
As for the OP, it all depends on how much you remember. For me, going through Uworld is like an exercise in smacking myself in the forehead in those gotcha moments. After reading the descriptions, I'll be like "oh goddamnit, I remember learning that" and I won't do much more than that. If it's something really out of left field, I'll go to First Aid or BRS-whatever and look at the concept that completely dumbfounded me.
