Mine are out 24/7. I put them in their stalls when it is going to thunderstorm or come a heavy downpour. Once I move them here to my house (in a couple more months) I will have a run in shelter open so they can get out of the sun or rain.
Mine are out 24/7 with run-in shed except when we have heavy rain or snow (I prefer them to stay dry and enjoy the hay in stalls then). I don't believe in stalling horses regularly - they get bored and develop nasty habits, they don't move enough, and frankly I noticed those big barns sometime even more cold inside then in my shed during the winter.
My boys are turned out 24/7 they have a run in lean-to shelter as well as a barn closed in on all sides except for a door opening.. only time they go in or under is if its raining, they also have tons of trees. Neither one likes to be stalled.
But my old dressage mare LOVED being in her stall, during the summer the horses would be in the barn and turned out at night, during the winter out during the day in at night and she absolutely hated it. She would try to run to the barn when we would bring her in.
Mine are out 24/7. They have shelter to run under to get away from the sun or rain. I do bring them up at night and contain them to the dry lot area overnight, but its still large enough that they can move around and even trot a little - which I feel is better than a stall.
Mine are turned out all day every day, only brought into feeding stalls to be fed seperately. There are plenty of trees for shelter and the stalls are left open so they can hang out inside if they wish although they rarely do.
Whilst I am sometimes envious of the beautiful pristine condition of the coats of other horses that are kept stalled all the time, I love seeing mine play together in their pastures. Even if they have all the nicks/bites to show for it, luckily most are on the back and covered by the saddle blanket he he.
I board my horse, so I do not get to choose how often he is out. If I had him at home (hopefully within the next few years, sigh), he would be out 24/7 with a run in shelter he could use when he wanted it.
However, a lot of the barns around here basically turn the horses out during daylight hours-- if the weather is right. So they are in if it is too hot, too cold, too windy, rainy, or what not. Drives me nuts. !!!!!!!!