Haynets is the best especially for young horses, a lot of my young horses get quite bored in the box so they play with there hay, so I usually put a toy for them and there hay in the haynet to not spoil it
You have tree solutions, the first you install a distributor in the stable. The fact of putting a distributor will allow both to regulate the doses and also not to waste. The second solution is to have a feeder to receive hay often in large stables, there are specific barrels. The last solution is to put haynets in the stable.
I hope this helps :)