We have 8 horses, mostly WBs and including a mini, some youngsters, a semi-retired mare, and some semi-competitive H/J/dressage types. They live with me. Most are ridden just 2 times a week due to my current work schedule.
I like them out as much as possible. In summer, they’re out all night (go out about 7 or 8pm when it cools down, and then back in the following morning when it starts to get hot, so between 8-noon), in winter they’re out all day (out between 7-10 and in between 5-8pm, and if it’s cold and raining during the day, they stay in). In spring/fall they may come in to eat and then go right back out.
When they’re out they have grass (in winter, we have winter rye and supplement with large bale timothy/alfalfa), and hay is fed in stalls.
I used to have a couple of horses live out full time, but have reduced the herd a bit, so now have a stall for everyone. Most of my turnout areas have access to a matted run-in with fans, so they do have shelter from the elements and the sun).
One mare is a princess and she may come in earlier than others, and obviously if one is on stall rest, I try to rotate the others so it has company. But in general, I really think my horses are happy when they’re out as much as possible. They have suitable outerwear, and we rotate the pastures to keep the grass healthy.