I don't think I have heard the monument story before. It sounds quite ridiculous, and is about as counterproductive as an example as one could think of, as it g

I don't think I have heard the monument story before. It sounds quite ridiculous, and is about as counterproductive as an example as one could think of, as it gets the 5 whys thinking completely wrong. Obviously there is nothing magic about the number 5 nor is it the case that every problem has a unique cause which has its own unique cause in turn. The point to asking "why" as many times as you have to is that instead of just solving one particular problem you want to prevent similar problems in the future. More specifically, instead of saying "the problem is human error and we fired the guy who fucked up", you want to improve processes to make human error less likely and/or less damaging when it occurs.