The Deer Lab at Auburn University has a 430-acre high-fenced facility. All the deer inside the fence are well known and documented.
During the 7-year-period from 2012 to 2018, biologists and grad students were inside the facility daily, working, doing research, taking samples and looking around. They found only 284 of 747 (39%) of antlers they knew were shed by the bucks during that period.
They analyzed the antlers they found, and determined from their records and data that the average age of the bucks that cast them was 5½ years. For the antlers that were never found, the average age of the bucks was 3½.
Bottom line: The larger antlers of older bucks are easiest to see and pick up.
Interesting theory: The antler collections of the best hunters who find 50 to 100 or more sheds a year are probably biased toward older bucks, and do not reflect the actual age structure of the local buck populations.
Astonishing reality: If deer professionals can only find 39% of antlers dropped in a 400-acre pen, imagine how hard it is for the average looker like you and me to find the sheds of wild deer in wide-open spaces.