I live in fear of forgetting to close the coop or the run door at night, worried about the day that I will have thought I did but I really didn't. If this happens and if my feathered friends get hurt or killed, it will have been entirely my fault, not the preds fault. Chickens are an accident waiting to happen and they are simply too vulnerable without our protection. They need us to never forget that. Daytime attacks will sometimes happen despite our best efforts (and I would say if this happens as much as you've had it happen, the birds should be in a large well protected run and not free ranging except when you are standing right over them) but nighttime, that's when they need to rest peacefully in a fortress.I pray I don't space out one of these days and forget to lock them up tight but I don't consider myself invulnerable to that mistake so I try to check and recheck, much like the folks that check their coffee maker 10 times to see if they turned it off before leaving for work, hoping they don't burn down the house.
JJ