Should I train to failure on every set?

No. Stopping most sets 1 to 3 reps short of failure gives you nearly the same muscle growth as going all the way, with much less fatigue. Save true failure for the last set of an exercise, and only on safe movements.

What failure means

Failure is the point where you can't complete another rep with good form. Training to failure feels like the hardest, most effective way to work, but the research says the benefit above 1 to 3 reps in reserve is small.

Why leaving reps in the tank is better

• Recovery. Failure sets take far more out of you, which can cut your performance in later sets and later workouts.
• Volume. If each set drains you, you can do fewer total hard sets in a week, and total sets matter a lot for growth.
• Safety. Grinding out a rep on a heavy squat or bench with bad form is how people get hurt.
• Consistency. Hard sessions that leave you wrecked make it harder to show up.

How to gauge it

Use reps in reserve (RIR). After a set, ask how many more good reps you could have done.

• 3 or more left: too easy for most working sets
• 1 to 3 left: the target for most sets
• 0 left: failure

It's tricky at first, because beginners tend to underestimate how much they have left. A useful rule is that if your last rep was slow but clean, you were close.

Where failure is fine

It works on exercises where there's no real danger and your form won't collapse:

• Machine isolation work such as leg extensions, curls and lateral raises
• The final set of a movement, after earlier sets were controlled
• Push-ups and bodyweight exercises
• The rep races in League of Fitness. The 60-second push-up, squat and sit-up races are all-out by design, with your phone camera counting reps against a real opponent.

Avoid failure on barbell squats, deadlifts and bench press without safety bars or a spotter.

What I'd do

Keep most sets at 1 to 2 reps short of failure, and push the last set on each exercise a bit harder. Track your numbers, as covered in progressive overload. If you're constantly drained, stalling or sleeping badly, you're probably pushing too hard too often, and a deload week may help.