Horse Stalling schedule?

I live here in va and my horses stay outside 24/7 365 days out of the year. They all have stalls....(2- 12x12x3 stalls shed row barns)(plus a 10 stall pole barn, which I store my tractors and implements in) and know where they are and can go in them any time they wish or into the run ins(12x20), but I never put them in there unless I am working on them or something. They are BLM Mustangs and 1 QH. They have been without shelter their whole lives before they came to me and the same goes for my gelding QH. He never was sheltered before I got him at 6. He was just left to run as an uncut gelding/a worthless stallion. So now they run here and there and everywhere they please. I have 25acres of fenced pasture turnout with running water from a cold water under ground spring and try to give them a natural type of horse life. I do not blanket them either. If the snow gets deep I go out with my snow blower and make paths for them and they are happy as pigs in****.
I can walk out and call them and any one that comes I can jump on and ride with or without a halter back in and the rest will follow and I have no troubles whatsoever in getting the one I want to ride sorted and singled out.
I can sort of understand about the show coat and all but why in the world would want to lock up your grazing animal in a stall/cell for X amount of hours a day? If I had an IR or Cushings horse I would use the dry lot/ sacrifice area, but not a stall.
How happy would you be living, sleeping, eating, defacating, urinating in the powder room bathroom?

Summer time mine are out 24/7 with access to shelter. I have 3 in one paddock during the day and 2 in the pasture then I switch. 2 get locked in a paddock while 3 are in the pasture. The paddock is split in half.

During the winter 3 come in at night while the other two have stalls that open to their paddocks. I leave them to decide whether they are in or out unless the weather is severe and then I lock them up.

I will take the pasture away as soon as the grass go's dormant. And won't give it back until spring.

Right now our horses are on a weird rotation. The geldings are kept in from around lunch time to midnight while the mares are out. The. The mares are in from midnight to lunch time the next day. Right now we have one pasture. So we have to rotate because we have one gelding that is severely mare aggressive. When we move all the horses will put up at night and then split up into separate pastures except for our black two who will kept in during the day and out at night.