I have over 3 dozen chickens. 16 hens that are under extended light conditions that when the all the marans synchronize and lay on the same day i get sixteen eggs. I have about that many large white Cornish also plus a 4 roosters for the laying flock. I feed free choice with feed being available 24 hours a day outside the coop in one of those metal tower feeders. A 50lb of Thunder chicken lay pellets last no less than 7 days and no more than nine days. I do throw cracked corn everyday, a lot more in winter than in summer.
There is a lot of waste going on for you guys. It can be blamed on sparrows, squirrels, mice and rats and even rabbits. But the first and foremost biggest feed waster is our chickens when they are fed crumbles or mash. Unlike pellets chickens can sort and will flick out mash and crumbles to get to those prized nuggets of corn. They're small but if you look closely at your feed, you'll see those golden nuggets and the chickens can see them much better. They will flick that feed out all day long to get to those corn morsels and contrary to misinformation chickens will not scratch around and eat feed off the ground when fresh feed is present in the feeder.
If you aren't going to feed pellets then wet the feed down so that when a handful is squeezed no water comes out but the feed maintains form. They can't flick it out. Or just switch over to pellets. It's the same as crumbles and mash, just a compressed form. I have 6X more chickens and my feed is lasting longer.