Whether you're new to lifting weights or have been doing it for years, you're just as good at guessing how many more reps you can do before your muscles give out.

When people lift weights until they're almost too tired to continue, especially with arm exercises, they get better at guessing how many more reps they could do. It's like training your body to feel its limits more accurately.

When people do more reps in a row during weight training, they become worse at guessing how many more reps they could do. This means longer sets make it harder to judge your own effort accurately.

Lifting weights until you can't do any more reps doesn't make you stronger than stopping a few reps short, according to a big review of studies.

If you're already used to lifting weights, going all the way to failure on each set doesn't give you better strength or endurance gains than stopping two reps short — at least over 8 weeks.

Lifting weights until you can't do any more reps makes your muscles grow bigger than lifting weights without pushing to your limit, based on a big review of studies.