I think it can go either way - either too harsh or too lenient. But it is irrelevant because there is really only the illusion of choice. if you don't choose a punishment the Dom/me agrees with then they will impose thier own ideas anyway. I think the true punishment in this situation is the dilemma of having to make that choice (knowing that the Dom/me is judging you as you make this choice) and, as Oz says, the sense of disappointment and negative self reflection.