At the NSPA, Philbin teaches that "Time Under Tension" should be maintained for the complete set. I.e. Do not rest the weight on your chest during bench between reps, or lock-off your arms on the upside.
A complete rep will take ~8 seconds:
1. ~3 seconds during consentric (muscle contraction) movement;
2. ~.5 second pause at top of movement;
3. ~4 seconds to complete the eccentric (negative) movement;
4. ~.5 seconds pause at the bottom before starting all over again.
I find that this slow deliberate movement is far easier on my joints, tendons, etc. and it ROCKS my muscles like nothing else. This is explained in detail in John's about HIT training.
Try this idea with push-ups... You will find that 10 slow prolonged push-ups (with a constant T.U.T.) will give you a far greater workout than 20+ push-ups that are hastily pushed out without a slow-smooth form.
-Rip