I’ve given swimming classes for beginners, but I don’t think I used anything like a token rewards system…
I did focus on praising improvements of every individual, but not as a way of fostering competition (which I guess is implied in a token rewards system).
The wide range in ages of those I was teaching (from 6 to 25) might have had something to do with not using a token rewards system.
I would think about implementing this if the group was homogeneous.