For hypertrophy, volume is much more important, but diminishing returns still occur with each additional set (6).
For starters, weekly volume per muscle group must be distributed in multiple sessions because research shows a pretty clear limit for the number of muscle growing sets in a workout (12,13,17,18). Even in advanced lifters, this per-session limit is around 5-10 sets per muscle depending on proximity to failure.
Beginners on the other hand, don’t even need much total volume to maximize growth anyways, so not much to worry about there (9,24). In fact, just under 20 weekly sets per muscle seems to be a surefire limit for beginners (11).
For advanced individuals, the hypertrophy volume recommendations become trickier. While we have some volume studies in advanced lifters, most of their designs don’t study above 20 weekly sets nor do they account for optimal frequency (14). Optimal frequency meaning the volume is spread across multiple workouts to prevent shooting pass the per session limit (5).
Radelli et al 2015 did a 6 month study using optimal frequency with volumes as high as 45 sets, but it was done in military personal untrained to weight lifting (19). Still they found higher training volumes were better.
Schoenfeld et al 2018 replicated this study using trained lifters (7). This study found muscle growth continued as high as 45 sets.
Brigatto et al 2019 compared 16 vs 24 vs 32 failure sets per week in trained individuals without optimizing frequency (20). Still they found 32 sets per week grew more muscle.
Does this mean higher volume is the way to go? Not quite.
Although these studies look promising and relatively accounted for the per session volume limit, these studies used suboptimal rest periods (<2 min.) indicating extreme volumes were only needed because the rest periods suck.
Aube et al 2020 slightly optimized for frequency and rest periods (21). They also made sure that not all sets were to failure and used highly trained subjects. This study actually found the lowest volume group doing 12 sets split into 2 sessions grew more muscle than 18 or 24.
Dellatolla et al 2020 gives us more insight(28). They compared highly trained lifters training low vs high volume for the lower body. By the end of the study, the low volume group did 14 sets of quad exercises while the high volume group did 28 sets of quad exercises. Frequency and rest periods were accounted for. The high volume group grew significantly more muscle and gained more strength. The only drawback is there were only 9 total subjects.
When considering the body of research as a whole, after accounting for optimal rest periods, frequency, and proximity to failure, I’m willing to bet 25 sets per muscle group is almost always the upper limit in practice (9).