Counting weekly sets per muscle
Training volume for hypertrophy is most often counted as the number of hard working sets per muscle group per week. For newer lifters, somewhere around 8 to 12 weekly sets per muscle is a reasonable starting range that drives meaningful adaptation without excessive fatigue.
Beginners respond strongly to relatively modest stimulus because the body is far from its trained ceiling, so large volumes are not yet necessary.
Why more is not better yet
Adding volume increases the recovery demand, and piling on sets before the body needs them mainly raises fatigue rather than results. Volume is best treated as something to increase gradually over months as progress slows, rather than maximized from the start.
Individual tolerance varies with sleep, nutrition, age, and stress. This is general educational information meant to describe common training principles, not a personalized prescription.