The hypertrophy series: the optimal number of sets per muscle group

First off, let us keep in mind that sets by themselves mean nothing if the value of reps is not expressed. As far as what is going to be optimal, it's whatever is going to promote strength progression which is going to be a reliable sign of muscle hypertrophy in the long term. For some, this can mean only 1 hard set. But the more you train, the more set multiplication becomes relevant, and in that context there are certain parameters to keep in mind.