I didn't say anything about "next time." I am totally on board with "you mastered it; it is no longer an obstacle for you" until the circumstances change. How did you get the impression otherwise?I think this is where the disconnect like. You think that the DC is 23 irrespective of whomever is attempting the climb and the next time they try it is also DC 23.
Is the wall as more like a puzzle. If Bob needs a DC 23 climb to climb the wall and makes it, he does not need to roll the next time he tries that wall. He knows the way up, no need to roll unless something has occurred to make it more difficult.