I would say that you shouldn't base your 4th year schedule around what's going to be helpful on the CK. Rather, take rotations which are going to help you for your residency application in whatever field you're applying in so that you have solid grades in those clerkships and you get LORs from faculty in those rotations. Unless you're doing some crazy schedule where you do psych followed by surgery and then OB followed by IM, there's no real way to be prepared for every topic on the CK through clerkships alone.