I think we're talking about two different things. Speaking only about standing and shooting at a target 10 feet away should be easier to hit than 20 feet. I'm only talking accuracy, and how practicing at distance will generally improve close range accuracy.
Seems like Gabe focuses on many different things, such as avoiding retreat, moving and dodging, rapid fire, quick draw and hand to hand combat. I was talking only about accuracy. I guess what should really be practiced for HD are the topics gabe brings up: