Pre-stretching string, specifically the practice of adding a percentage of reference tension to a pull, does exactly that and that is its only intention; to remove elasticity of a string and thereby take away some of its power. I really shouldn't ask, but what do you think pre-stretching is for? Personal experience can be disputed when the method used to replicate an action is flawed or if the nomenclature used is different. You say you use a drop weight and "add weight" to the pull. You state you're using 20 kg of extra weight on each pull? Clearly there is a disconnect. One must consider if they are the only voice in the wilderness that maybe they are wrong? I'm certainly not in the league of some of the stringers who've refuted your misguided interpretation of one video, but I do string and I string for a WTA tournament. I have never been asked to pre-stretch poly using the aforementioned definition of pre-stretching. I have, by two or three players, been asked to pre-stretch natural gut. The percentage they requested was 10%. I have to say that asking a question, getting the answer you don't want from people who know, and then continuing to argue is the definition of trolling.