When I set up along a deer trail, on the ground with no blind using available cover, it is the yardage that the cover gives me. I have had deer pass me at a few feet that I couldn't feel right about the shot, but then shot them at more than 20 yards when the shot was right. Shot timing is one of the last things most hunters learn. It is not set in simple rules. 20 yards and in is what most instinctive shooter and three under shooters use because, depending on the set up, that is where arc comes into play in archery. I have lost track of how many wired deer that I let go by regardless of how close they were. It is easier to have a shot at an unaware deer at 25 yards, when still hunting or hunting on the ground, than one at 10 feet. I like still hunting for deer, but the cover has to right, cedar shrub covered slopes being one, things can get very close. Being fast, smooth and sure of yourself is a big plus in those situations, you may only a two or three second window to take a 12 foot shot.