Has it occured to you by working legs with less sets than the upper body, maybe that's the prime reason that's it's working "too well" and your legs seem out of muscular balance. One day a week for the legs and three day for the upper body should give some clue that you might be overworking the upper body by not allowing enought recovery time. Of course having a single workout day for the shoulders may not be the best idea in the world either. May want to readjust the weekly split a bit, adding more sets is usually not the answer for lagging body parts. Personal view is that your doing ways too many sets for all the exercises per muscle groups anyway, including legs. Good Luck.