Mill Creek Keto What's this got to do with the size of the class? Well getting everything correct in a class can be quite challenging, and participants will need hands on correction from the instructor, however experienced they are. Even in my small group Pilates classes, which I have a maximum of 7 people, it can be a challenge to ensure safe and effective exercise with such a small number (hence the limit of 7 people). I remember attending classes at Leisure Centers such as Virgin Active & Everyone Active, where the classes had an average of between 25-35 people, it was impossible for even the most talented instructors to ensure safety and correctness when delivering a class, because of the sheer volume of people there.