Really? Doesn't that make you crane your neck? I tried that in the past and it makes my neck hurt. When I google terms "computer posture" and go images, what jumps out at me is that the screen should be at or below eye level. I guess whatever works for you works, but why do you think one should look up at the screen in general? I'm curious, because I've never had good body awareness, and it's possible to learn little things that make a huge difference, I find.

Seems the really important thing is back posture, which relates to sitting angle, etc.