I get accused of using a modded controller quite frequently, and thats intersting actually, because even though the picture I have above is meant as a joke, its not really all that funny since all the thought into it was due to actual need. My fingers dont work well anymore. I cant grip anything small ( good thing I'm married ), my fingers usually wont bend all the way, and when they do, some of them get stuck there and wont straighten.
Not long ago I was fishing and the first cast I threw my pole in the water .......... first time ever in 47 years, I frequently have cups and such just fall out of my hands. When I'm driving I have to switch hands every couple minutes because of cramping, and the backspace button is the most used button on my keyboard since I cant seem to hit one key at a time.
Now I'm not saying all that to complain, but I want to make a point about something. I attribute my ability to fire fast to my hands not working well. I seriously think most people's problems trying to fire quickly is because they fire too fast. If you fire too fast you hit the rate cap on most weapons and throw the whole timing off. I very seldom can hit the rate cap but my quickest feathering of the trigger seems to hit just under it.
Soooo ........ I guess my suggestion for anyone who wants to rapid fire like the best of them ....... start carrying things with your fingers hooked that are too heavy to really carry at all, smash your hands with a hammer a few times ........ maybe even punch a few walls or something, and maybe 15 years or so down the road you can imitate a modded controller like me.