Generally, the maximum number of repetitions RM is often used to express the load intensity of strength training, that is, the maximum number of times an individual muscle can overcome a certain weight.

Fitness is generally to develop muscles, generally using 50% to 75% of the maximum load. The initial load is about 12- 15 times. Your coach arranged 10 to 12 times for you in each group. Maybe he has his own considerations. This amount and intensity can basically achieve fitness effect. If it is increased, each group can be as high as 20-25 times.

This also varies from person to person. I usually communicate more with coaches and pay more attention to my own training, training, summary and improvement.