If you do the same total amount of weightlifting work each week, doing it all in one session will build your muscles just as much as spreading those workouts across multiple days.

We don't currently have enough proof to say whether working out a specific muscle group three times a week builds more muscle than doing it twice a week. Because the research isn't clear on this, experts can't yet recommend training muscles more than twice weekly for growth.

If you work out the same total amount, splitting your muscle workouts to hit each group twice a week builds more muscle than doing it all in one day a week. Basically, spreading out your training leads to better muscle growth.

If you lift the same total amount of weight each week, it doesn't matter if you do it all in one day or spread it out over two or three days—you'll build the same amount of muscle. Your total weekly effort matters more than how you split it up.

If you lift weights more often each week—like 3 or more days instead of just once—you might see a little more muscle growth, but only if you’re not doing the same total amount of lifting in both cases.

Taking breaks from intense workouts every few weeks doesn’t reduce your overall training volume or stop you from building muscle in the long run.