Stephen...I agree...sorta. Have you ever hung a line in a tree that had a WLL stamped on it? If not then you are guessing. It is about making educated GOOD guesses, but we work in nature and to preserve natural settings. Not everything can be a perfect known. By no means is this an excuse to half-ass safety inspections (if anything it is a call to more diligent)! We have to work with contingency plans in place when we are guessing. Often times it is the lack of Plan B as much as a bad Plan A that will cause trouble.