I see so many people saying to "only do 3 exercises per muscle group" and "only do 12 sets per muscle group", otherwise you're overtraining...
To my understanding, overtraining is working out a muscle group too soon after having worked it out before. So can someone explain this?
It's easily possible to do 15-20 sets on a particular muscle group in around 45 minutes. And if that muscle group is only being worked out once a week, how is this overtraining?