I think it depends a lot what kind of "punishment' we're talking about. Usually my legitimate punishments consist of "boring" activities, like corner time. I prefer to use SM activity for fun, and not always as punishment.

If a sub was the kind that did see SM activity as good for punishment too, I still wouldn't do anything with that until after the other more boring activity, both because it's effective, and because if I was legitimately upset, cool down time is sensible. I don't believe in doing SM activity with a sub while I'm upset. For lack of a better term, I think it's messing with bad mojo. People make mistakes when they are upset, control lessens. And I think control dugin such play is vital to the experience not becoming a bad one.