The gear shift on automatics "clips" gears..... meaning if you drop it to lower gear the car will continue to shift normally in the first 3 gears - just never getting into 4th.

Maybe if you're driving in situation where you never need 4th, say under 45 mph in traffic, then dropping the lever one gear lower will give you the performance you want.

Naturally when you upshift the lever to grab 4th gear (when you want it), easing off the accelerator will provide smoother shift that wont tax the tranny.

Most people never touch the shifter on automatics - i dont know why.