My three gelding live out 24/7 with a 40’ X 10’ run in shed. We have gone away for up to 6 days at a time and left at least 2 at home. We have a 13 acre pasture that they have access to, as well as 2 acres of dry lot. We have a spring with a 400 gallon concrete tank to hold water plus another 100 gallon Rubbermaid trough in a different area for easy water access. I have a neighbor who stops once a day to check on them. When we are gone in cold weather, I put out a round bale in a feeder that will easily last them 2-3 weeks.
I’ve owned horses for close to 40 years and I have honestly had more injuries and issues when my horses were boarded and stall bound with limited turnout. As I sit here thinking about it, the only really major problem I have had since having horses at home for the last 20+ years was with a horse I got in from my ex-husband in my divorce, who had been twice foundered when I got him. Dry lot and muzzle have resolved that issue nicely, although I do watch him carefully during spring and fall.