You can do them on every exercise if you like, but I would reduce the overall amount of sets you do to avoid overtraining/stressing the muscle.

I usually do it on my first exercise which is usually a big one - Bench, Squats, Shoulder pressing etc

I then use supersetting for the smaller shaping exercises afterwards. E.g cable crossovers and pec deck flyes.

Arnold used to superset bench press with chinups. Try it