Getting a maximum range of motion is key to good calf development. You see way too many people at gyms just bouncing that shit on the seated calf raise, usually with a weight they cant handle. When all they really need to do is focus on the contraction at the top and get a decent stretch at the bottom of the movement.
Switchin up your # of reps seems to help also. I like to get a few high-rep sets in, but also do a heavy set or two on seated calf raises. I like Leg Press Calf Raises also b/c you can use increased poundage and its easy to switch foot positioning.