Fanning is pure hollywood
It's really tough on your parts and is not anything you want to do with a single action. It also trades accuracy for speed.
There is a sometime poster on the forum called Jim March. He carries a Ruger New Vaquero in .357 in a fanny pack and has documented a lot of his custom work he's done to it. Interesting take on a self defense handgun(not for me) but proficiency with any weapon is better than nothing. The .357 is considered to be a near one shot stop so he's probably not limiting himself too much in the defensive shoot category.