There should be no such thing as estimates in the field. There should be no such thing as estimates. If the yardage isn't known, it's a no-shot situation. Use a rangefinder! If you don't want to use a range finder in the heat of the moment, mark off distances around your stand. You know if that deer is halfway between that tree you've got marked at 30 yards and the bush at 40, it's a 35 yard shot. A little closer to the tree, 33 yards. A little closer to the bush, 37 yards. No guessing.

This is and always has been a matter of bowhunting ethics and I hate to see people using arrow speed as a substitute for good ethics.