Right off the bat, a caveat: not my barn, not my horse, not my choice of stable management. I was paid to do night check (check horses, top up water, throw extra hay if necessary) at a barn I was boarding at.
I found a 2yo colt with his halter clipped to his window grate. 2yo colt was wearing the halter at the time :o Thankful he was a pretty level headed Standardbred in training and not any of the other goofy creatures it could have happened to. Oh, wait, none of the riding horse owners allowed their horses in stalls wearing halters, and even if they had, they would have done the clip up the right way (against the face) so it couldn’t get caught on a window grate, or anything else in their stalls or on anything in the pastures.
Earned a few more grey hairs in the few minutes it took me to figure out how best to extract the horse without causing damage to either of us!
In the few years I did that little job I also found a few other run of the mill things - stall doors not fully latched, outside door not fully latched in winter :o lamenesses in old horses (abscesses usually), minor eye injuries, etc. And one degloving injury in an out 24/7 horse. That was nasty. Although the horse would not have died from it if left overnight, it was definitely an emergency vet call to get it patched up and healing as quickly as possible.
Night check is never wrong. In a well-managed barn, 99+% of the time, you should find horses munching and nothing out of the ordinary. But that tiny micro percentage is worth boring yourself to tears doing it every. damn. night. of. the. year.