But fighting is chaotic. It's often unpredictable. It doesn't systemize well and it's difficult to pass on as a body of knowledge. What people don't realize is that no matter how effective the founder of a discipline may have been in his (or in the case of Wing Chun, her) day, unless the practices of that system involve rigorous testing in realistic fighting conditions against non-compliant opponents from outside your system, you can never really know whether you can make their moves work for you.