My best practice is with judo heads at unknown distances. I have a woods road on my place that's perfect for walking and picking targets up ahead. I try not to think how far, just look, feel the gut, and shoot. I try to reach out on purpose some of the time, and then pace to the arrow to see how far it was. I vary the routine with really close shots too, because I've missed close shots on game from practicing long ones too much.
In the back yard I have targets 5 yards apart, and vary how far from them I stand, so I don't get locked in to a single sight picture. I want to feel my gut every time, because that's what works the best for me when I don't know the range. Generally I try to keep shots on game to 20 yards or less, but I've killed a deer at 35 (didn't realize it was that far when I shot) and an elk at 55. That one gave me a couple of practice shots by coming to my bugle three times! Oh yeah, and a rabbit at 55 too. My brother was with me, and he said he was going to tell me it was a terrific shot until he saw the look on my face. I was astonished that I hit it, to say the least, and I guess is showed.