As long as it didn't violate some principle of safety, I don't get wound up too much how it is done. Sling shot, hand over, slide stop, no biggie.
The one that did use to make me cramp a little is when shooters would COUNT on being able to make the slide jump forward and chamber a round by slamming a fresh magazine into the pistol hard enough to bump the slide forward. It works all greasy when it works ok, but those same shooters tended to look like a center fielder who just missed an easy pop fly when the slide stayed locked to the rear.