This is where the ability to teach without participating can make all the difference in the world. When I put on my “educator” hat, I can instruct clearly and effectively without needing to get my own workout. It takes mental energy, but it doesn’t wear and tear my joints.
So, for me, my maximum in a day is 4 classes. 2 in the morning (one cardio that I’ll dance along with and one small-group that I’ll demonstrate but mostly instruct) and 2 in the evening (one small group that I demonstrate but mostly instruct, then a yoga class that is mostly restorative).
Normal class load for me = 14 classes a week, which gives me a good work/life balance.