One hard workout a week won't replace three moderate ones at the same volume

Training frequency affects results independently of total load

There's long been a debate over what matters more for muscle growth: total weekly training volume (the sum of all sets and reps) or how that volume is spread across the week. Studies that equalize total volume between a group doing it all in one weekly session and a group splitting the same volume across 2–3 sessions more often find an edge for the more frequent split, given equal total volume.

The mechanism ties back to muscle protein synthesis being elevated only for a limited window after a strength workout — roughly 24–48 hours for most people, after which it gradually returns to baseline. Training the same muscle group once a week means a large chunk of the week passes without an active growth-stimulating signal, while training that group more often keeps protein synthesis elevated more of the time.

Practical takeaway: if training time is limited, it makes sense to spread total sets for a given muscle group across 2–3 sessions a week instead of dumping the whole weekly volume into one exhausting session — the resulting growth stimulus is usually higher for the same total number of sets.