Hi Esta. The answer to your question depends a lot on a couple of factors: they type of group class that’s involved, and the degree to which the instructor is an ‘active participant.’ For example, I train teams and small groups of athletes. Depending on the actual session involved (e.g. is it a weight training session, or something like a plyometric or speed training session) my active involvement varies. If I were to try to actively participate in several plyometric training sessions in a week, I might find myself injured, whereas if I’m merely supervising and/or demonstrating a weight training session, I may be able to do several of those in a week.
So, take a look at what type of group sessions you’re talking about and see where that answer leads you.
Good luck, and stay healthy!