Well, talking like this keeps the phone from radiating into the head from zero distance and angling it in this way puts your mouth closer to the microphone, so if it's over, I say, "Don't let the door hit you on the way out. "
Neither of those things provide a measurable or meaningful improvement to anything. The phone is designed to be directly against one's head within allowable safe levels of radiation. And the microphone/audio processing is designed to pickup sound from the standard phone position.
I'd say 'you do you'...but actually, you shouldn't.