They are and you are always trying to increase work capacity, these will do it. Allows you to get about 30 reps in with something you would normally do a hard 15 with but you get several more hard and challenging reps in. You know the effective ones. They are good for any exercise that once the weight is set you can start back up quickly. Just avoid anything that wouldn't be safe to fail with since that is part of the goal.I think I’m going to try some muscle rounds out on leg curls or something if I can remember to. They sound fun.