If you're someone who's been lifting weights for a while, splitting your workouts into 2 days a week works just as well as doing them 4 times a week — as long as you're doing the same total amount of exercise over time.

If young guys lift weights all over their body 3 times a week for 9 weeks, they'll get stronger — no matter if they switch up their exercises or stick to the same ones.

If you're already strong and lift weights, training each muscle group either once or five times a week for eight weeks will give you about the same strength gains on the bench press, squat, and row.

If you're a guy who already lifts weights, doing full-body workouts five days a week will make your forearm and thigh muscles grow bigger than if you only work each muscle group once a week, after eight weeks of training.

If you lift weights the same total amount each week, it doesn’t matter if you do it in one big session or split into three smaller ones—you’ll get just as strong and build just as much muscle.

If you're already fit and lift weights, doing way more sets (15–20 per muscle group per week) doesn't make you stronger faster—in fact, you might even gain less strength than if you stick to just 5–10 sets.