I would prefer 24/7 turn out for most of my horses, but they don’t always agree with me.
I’ve got a couple that grew up with me at western pleasure barns like described in this thread. Where they were out of their stalls several hours daily, but it wasn’t at their leisure. They were out and about and moving. Even now, at 10 and 12, when I turn them out and it gets too hot/buggy/starts lightly raining – they run the fence line and work each other into a lather. If they’re turned out separately and any of the above happens, it’s 10x worse. I’ve seen them seriously consider attempting to jump the fence.
I’ve got a couple of older mares who won’t lay down and really sleep unless they’re in their deeply bedded stalls. Never mind that they have pasture, big soft round bales, etc - they want the padded stall and big piles of shavings.
My personal horses stay inside during the day (Texas, summer, bald faced paints that burn), and go out at night. And then it swaps in winter when it’s cold.
I’ve seen horses that do okay with “no turnout like never ever”. It’s usually quieter breeds that go along with it better. And, again, when I’ve seen it - they go out on the walker and then they’re ridden and then they’re asked to stand and be patient. I don’t think it’s a best practice, but if the option is that or more barns close up shop, I’ll take stalled horses any day. I’m tired of losing people to the industry because things aren’t “perfect”. Perfect is the enemy of good.