Not going to flame you but my experiences are vastly different. I have seen hundreds of good shooters miss a target at 10 feet by point shooting and not indexing their sights.
I'm actually a decent point shooter but would never try to break a shot in competition or in a self defense situation without seeing my sights on target.
Sure you can sight down the side of the slide and/or the top of the slide but why would you? if you have time to sight down the top or side of a slide it doesn't take any longer to actually use the sights.
If not using sights is faster than using them(and still hitting your target) then no competition shooter or self defense instructor would even have sights on their gun.
You or I getting lucky on the range point shooting or not using the sights and hitting some targets is totally different than doing it in competition or in a for real self defense situation.
You are correct it is a function of muscle memory and that holds true for using the sights as well.
The more you shoot the more you get to know what the "acceptable" sight picture is and what you can get away.
Great topic for discussion
