It is always just for the pleasure of a sadistic mistress. But you are right, there were also really, really sadistic ladies, who tortured me so extreme, that I asked to stopp. Not because of saving my manhood, because of my manhood was already demanged of some sessions before.
every sub seems to wish for himself some punishment from a sadistic mistress... but are you really able to stand still on a real caning or CBT session? or to cope with the fear and pain of the the next coming stroke? All of that just for the love of your sadistic mistress?