Here's my theory, I have very skinny calves and never really got them to grow much in the past. I would train them once a week. I'm thinking now I should train them every workout which is every other day. I see the road bikers who have great calves and some of these guys ride 60 miles a day. Make sense? I have been doing varied workouts on them each time also. One day I will go heavy, next time more volume less weight and I even do the 100 rep routine. I know I wont get huge calves due to my genetics but hell I at least want them to look like I workout.