Not so...Haha
Right. The SabumNeem won't ask anything of the student that shouldn't be asked. Their judgement shouldn't be questioned! If they say to do it, then they know what they are talking about!
If the Master Instructor says to do something, then Yes you will do it!
Period
I've asked students to do things they physically can't. Or psychologically can't. Sometimes, it's been deliberate -- to drive a point home about their ability. (Yes, sometimes failure is necessary to get through to someone.) Sometimes, it's been accidental. I didn't know until they either failed or freaked out.
Part of martial arts training is about confronting limits and being uncomfortable. If all you want is to have fun and never be pushed, take a taebo class or something.