What do folks use to determine their effective range? Mostly, wishful thinking and some self-delusion. I say this tongue-in-cheek, of course, but i do think most overestimate their effective range.
When I taught Bowhunter Education, we used an activity to help students develop a realistic view of their effective range. We asked them to write down their personal effective range on a piece of paper. Then, we later took them to the range with a steel deer silhouette with a hole for the vital area. We then asked them to go to the effective range they wrote down and shoot through the hole in the target. Voluntary, of course.
When faced with the actual challenge, and the possibility of a broken arrow, most declined. And most who shot, broke their arrows on the steel target. This included more wheelie shooters than stick bow shooters, but the principle holds.
Most of us think we're better shots than we are.
Too, it's lot different shooting at a critter in the heat of the moment than it is in a relaxed setting on the range. Effective range decreases even more when actually hunting.