I see a difference between the competitive sparring tc1o1 is talking about and drilling things realistically. The Inosanto Academy guys call it "progressive sparring." Its more like our "Gor Sao" training, but not necessarily against an opponent that is also doing Wing Chun. You can "pressure test" certain things without just jumping in the ring and sparring. In a competitive sparring situation there may never be an opportunity to apply certain things from Wing Chun, or the student may just not THINK to apply them! So they never really get trained. That's why guys that just spar all the time end up looking like some form of kickboxing. Its because this kind of sparring doesn't necessarily bring out good Wing Chun technique.