Yeah, I do standing raises also in a squat rack, but I do them different than regular muscles, I progress the loads, but I always just do 20 reps, since calves are so strong and tough and also have alot of slow-twitch fibers, and insanely high endurance...(walking around all day long....calf work.) It is amazing how much weight I can do 20 reps with calves compared to other muscles, which would poop out doing high reps.