Much of the current training emphasizes tactical reloads vs. emergency reloads. So, manipulating the slide is done less often. In a fight you don't want to ever find yourself with a slide locked back because it means you are out of ammo! At least for a bit. With a tactical reload you're never totally empty.
But when you do need to release the slide, slingshotting is preferred for the reasons noted above plus the fact that it gives you a quarter inch or so more spring action. Assuming of course you have 2 hands available. With just one, then slide stop release is it, obviously.
And, the malfunction clearing drill is now slap, rack, ROLL. Slap the mag, rack the slide back, hold it and roll the gun to the right to allow gravity to pull out any round that has been cleared. Then release slide and go bang.
If you want to shoot...shoot...don't talk! Tuco
USAF Munitions 1969-1992