"If anyone has done most of those experiments they haven't advertised the results. Clerics are tougher than average but not five times tougher than other people with similar careers, but they mostly do not self-injure before doing a healing surge and she doesn't know anyone who has tried it. If it goes by importance it's not in a 'you immediately become tougher when you get a promotion' way.
Notably it's at least a little tricky to tell how tough people are and it does vary a lot even among wizards of the same circle, unlike strength of aura which goes directly by caster circle. Keltham probably is hard to injure, she'd expect."
She agrees that none of this is how Civilization would explore the question. It's - pretty normal, for questions here.