Training frequency is more important than volume. Just 1 set done twice per week is better than 8+ sets done once per week. This is because high frequency allows very little volume to become much more productive due to less time for muscle atrophy to occur and more per-set growth when volume is spread out comparatively as there will be less fatigue impacting us at a brain level when training and thus reducing motor unit recruitment levels. When looking at frequency studies that actually use recoverable volumes, the higher frequency groups consistently beat out the low frequency groups for this very reason. Muscle fiber growth stimulus (MYOPS) lasts around 48 hours post-training then the fibers start to atrophy thereafter. So by doing 1-4 sets, allowing the muscle to recover back to baseline, and then training it again with 1-4 sets, we grow more by allowing for less atrophy throughout the week whilst providing the target tissue a better growth stimulus due to less fatigue. Intelligently managing fatigue and spreading out the volume so it can become more effective is how we get the most out of our training. To elaborate further into detail, we can express the hypertrophy stimulus as one arbitrary unit of the first set, then for each subsequent set, the growth stimulus worsens significantly due to fatigue. Every subsequent set is less than half as stimulating as the last. ..and when looking at maintenance literature, we know 3 sets once per week will maintain size for a given muscle. This means there are 5 days of atrophy (MYOPS elevated for 2 days in the week) total. The growth made from 3 sets after the 48 hours of hypertrophy had settled is lost in 5 days. This makes weekly volume a useless metric as training frequency has a large effect on how effective that volume actually is. ..so just saying you do 8 sets per week for a given muscle doesn’t really tell you much. You need to specify what the frequency is for the given muscle. If, however, you’re using high frequency, doing between 2-8 sets per muscle group per week with the sweet spot being 4-6 will probably be best. High frequency paired with a low volume approach, training 3-4 days per week, is best for muscle gains. Managing fatigue is important, do not overlook the importance of rest days. This is how I program with my training groups using Upper Lower and Full Body splits and we’ve seen some of the best progress and results yet.