Let's say a person will be doing 3 Sets of Flyes. After reaching failure (or close to) in his first set, there will be naturally the burning sensation and soreness all over his chest. Thus this person rest while awaiting for the 2nd set.
However, should the person only begin his 2nd set (and so on) ONLY when that burning sensation is totally gone from his Chest, or should he proceed nonetheless once the limited rest time is over (even when the chest has not totally 'recovered')? What difference does it make?