jesus christ! I'm giving advice to the fuckin' CEO! LOL...
I wouldn't use those techniques too often because you can overtrain that way. I generally get a feel for which group is ready to be absolutely blasted and hit it with a drop set, superset, 21's or flex-n-hold's when I feel fully recovered and rearing to go. If you push your body to failure and know what overtraining feels like (which I strongly recommend at least every so often) then you know when enough is enough and you let it rest.