I’ve studied four systems of Wing Chun.
Admittedly, I never got to far in two of them (one month and a year and a half, respectively).
But in the third system, I basically went nearly as far as was possible.
Yet when I started studying the system that Greg got from Gary Lam via Wong Shun Leung, I found a whole bunch of extra stuff in it!
Gary Lam had added the Muay Thai, but there was a lot of material from Wong Shun Leung (and I assume Ip Man) I’d never seen before. Outside of the mindset and the “taking position” ideas, I don’t think these elements are the most important aspects of the system, but it does give you a certain ability to flow with opportunity and to deal with adversity and changing fortunes.
What was missing from those other systems?
Pushing, pulling, tripping, standing grappling, and much of the kicking. And Po Pai.
I think integration of pushing, pulling, kicking, Po Pai, trips, with hitting adds dimensionality and surprise to the system. You can see it in the demo from Wang Zi Peng (a Wong Shun Leung student who teaches in China) below. Most of the stuff in his demo is in the Wong Shun Leung system (we have Chokyu standing grappling), but Wang Zhi Peng may also be playing with some Shuai Jiao (Chinese system of grappling and throws). This is what someone can do after they have mastered Wing Chun. They can use it as a frame for their other skills and talents. It can all blend together into a personal expression (as Bruce Lee would say).
These are all actions of opportunity. You don’t quite get into the right position, so their missed punch can turn into a pull. If they get traction, you can switch to a push, or a trip, guiding their head into a wall of the ground.
If you miss one kick, you can go with another. If you regain to the ground too close, you might have the opportunity to turn then and use a lock to disrup their balance. It all depends on what the opponent and the moment gives you in terms of opportunities.
But at the highest level, this ability to move between ranges and find opportunities at any distance is something beautiful to behold.