Whether you rest 1 minute or 2.5 minutes between sets, your strength gains in squat and bench press end up being about the same after 10 weeks of training.

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 already trained, doing light weights with short or long breaks between sets gives you about the same strength boost in your chest and legs after 8 weeks.

If you're already strong and lift weights regularly, doing 10–15 hard sets per muscle group each week for 2 months will make you stronger and add a little muscle — whether you train your whole body every day or just once a week.

Even if you’re already strong—squatting almost twice your body weight—adding more sets will make you stronger, but won’t make your muscles grow more than doing a moderate amount.

Doing short bursts of heavy lifts with brief rests in between can make you stronger in squats a little more than doing regular sets, if you're already trained and doing the same total amount of work.