I think it depends on where you stand with physio. If your NBMEs are consistently low in physio then it's probably worth it for you to take the time to review BRS, but if you're doing fine in physio on NBMEs then you probably already have a good physio foundation and will be better off doing more questions/passes of FA and pathoma. I took the USMLE a few weeks ago and I would say that the "reasonable" physio questions could be solved with UFAP knowledge. Just make sure it's a weakness before you spend extra time on it. Good luck!