I have stalls. But my horses go out at 3 p.m. And come in at 8 a.m the following morning. They are in their stalls for appx 7 hours a day and fed three times during that time. They have fans blowing on them and a radio plays in the barn all the time (country music is their favorite)
I really think they enjoy their stall time. It's too hot in summer for them to be out in the blazing sun.
In fall and winter they usually come in to eat and I turn them back outside, so they are in the barn very little.
When I move, I am thinking of doing run-in type shelters, but still want a place to be able to put them if I have to confine them for injury, etc.