I know these other styles better that most. I have trained in lots of wing chun other the years, then I found CSL which answered all the problems I was having. I have rolled with many guys with 25+ in lots of different branches, so I do know what I am doing works just fine. I never said others have not tested their wing chun. I have a friends in WT and other systems that have. I train with friends in other styles of wing chun. We don't all have the same ideas but we can workout together. It is just clear that many wing chun styles or people do not test of push out of the comfort zone.