The definition of madness is to do the same thing repeatedly and expect different results.
This is a true statement, but like all truths, there are exceptions.
There is huge value in repetition.
We do repetitions of an exercise in order to gain from it, to develop from it.
In the gym and in skill training, these repetitions are focused, you are present, mindful, in "the zone" or that mythical "flow state"
Each repetition is done with the intention of making it better than the last.
Making the the movement more coordinated, smoother, stronger Getting that movement to imprint itself deeply into the brain so that next time it can be done even better.
This isn't madness.