if you look at the mechanics or the shoulder muscles and the way the fibers run and actually flex, when you're doing shoulder presses the load is prety much taken by the anterior delt. I know that the medial head may act as a support group but by how much during pressing? enough to spark growth in that area? in my opinion the only way to properly add width to the medial head is with heavy laterals, and upright rows ...??? but someone correct me if im wrong.