Volume is the real driver
Research consistently shows weekly volume, roughly 10 to 20 hard sets per muscle, predicts hypertrophy more than how often you train. Frequency mostly matters as a tool to accumulate that volume with good performance.
Frequency and volume are separate levers; total weekly volume drives growth, and frequency just helps you fit it in.
These are not competing choices, they are two knobs. Total weekly volume of around 10 to 20 hard sets per muscle is the main driver of growth, and frequency is simply how you split that volume across the week. Higher frequency lets you spread the sets so each session has fresh, high-quality reps, but if weekly volume is equal, spreading it over more days is only slightly better, if at all.
Research consistently shows weekly volume, roughly 10 to 20 hard sets per muscle, predicts hypertrophy more than how often you train. Frequency mostly matters as a tool to accumulate that volume with good performance.
Doing 20 sets for a muscle in one session means the last sets are junk from fatigue. Splitting the same 20 sets over two or three days keeps each set crisper, which is why hitting a muscle 2 to 3 times a week is a common recommendation.
If you train 6 days a week, higher frequency comes naturally; if you train 3 days, full-body sessions raise frequency automatically. Pick the split that lets you hit your weekly set target while recovering, rather than chasing frequency for its own sake.
Frequency and volume are separate levers; total weekly volume drives growth, and frequency just helps you fit it in.