I’m in a rather special purpose built self board facility, where each stall holder has a loft the same size as the stall, 11 by 11 feet, right overhead. The lofts have doors and padlocks. You can get about a ton and a half of hay maximum in there and several feed stores or hay growers deliver.
I can’t imagine having a self or part board situation where my hay and feed wasn’t sequestered. Ok, under lock and key, paranoid as that sounds. The temptation to “borrow” would just be too great. Maybe even for me
I count my bales and weigh my feedings and know exactly how long a bale in a particular batch will last and my cost per pound. It would make me crazy if there were constant borrowing even if folks asked.