[oldE]

Uncle Billy,
I think what you are calling a wedge, I would call the notch. To me, a wedge is a wood or nylon piece placed in the kerf on the back side of the cut to stabilize the tree so the bar isn't pinched if the mass of the tree is not helping it go where it needs to fall.
I agree, the remaining wood between the notch and the main cut will control the direction of fall, if you do it right.
And that guy's chain is duller than mine!

Milt,
Many years ago, I worked for a couple of winters with a guy who was always blipping the throttle, possibly a hold over from days of running a saw which wouldn't idle. The boss used to remark that the guy cut twice as much air as wood.
Best
Les