I don't know. As I said earlier, I only really have experience with fencing (and mostly with saber), but real parrying does happen there. And sabers are extreme

I don't know. As I said earlier, I only really have experience with fencing (and mostly with saber), but real parrying does happen there. And sabers are extremely light and fast. (It feels a little silly to bring fencing up as the example when I just talked about how it isn't entirely applicable to the real world, but I think this part is.) It isn't just parrying in a vacuum--it also involves good timing, footwork and some forethought. It's definitely not based entirely on reaction time. For example, if you're moving backwards while parrying, you get significantly more time. Also, having a good idea of where somebody will attack (for example, you feign an opening) helps. And, of course, you do a ton of drills about how to parry so the different parries are burned into your mind. It still isn't anything like the movies, of course, but it is still significant. It also affects the right of way, but only if the opponent does not get through your parry, so parrying well is important even in the framework of the rules.