My long-range shooting experience and knowledge may be dated. But, when I was young, scopes were not considered precise enough to change "clicks" to adjust for elevation at long distance. Therefore, we generally zeroed at 200 yards and consulted ballistic tables for hold-over at the various distances, confirmed with firing, made out and attached a range card to our rifles (Except we used a "battle sight" setting on our M1's that resulted in shooting level with a standing man's shoulders at 400 yards, at his knees at 75 yards.).
Are scopes really that reliable now that if they were clicked up to 800 yards or more from a 200 yard zero, clicking back down to 200 would return to a perfect 200 yard zero?