I studied Sil Lum Kung Fu when I was a younger, thinner man (in my early 20s, to be precise). I learned three important things
1) How to throw a punch hard without breaking my hand or wrist.
2) How to minimize the pain and damage of falling.
3) How to ignore pain, to a degree.
Everything else was either pretty much for show. I appreciate what I learned, but as for actual fighting, one pretty much learns that by getting into fights. Whether those are formal martial arts bouts or getting into bar room scraps. That last flows from the concept that if you get your ass kicked enough times you figure out ways to not get your ass kicked.
I remember when my sifu went to demonstrate "pressure points on me", and hit me in a spot that was supposed to be debilitating. When he hit the spot I told him "Well, I would rather you didn't do that any more. But it's mostly just annoying"
I became very skeptical of martial arts after that.