It depends on a lot of things - style of feeder, type of food, where the feeder is located, your climate... Standard poultry feed is dry and has a long shelf life, provided that it doesn't get wet somehow. I wouldn't trust a feeder kept outside, even in a covered run. Moisture has a way of getting in there if it's outside. Better to keep it in the coop where it's protected, or change the feed more frequently if it's outside.
I have two feeders. A small trough-style feeder that sits outside (in the covered part of the run) which I only use for the wet mash that my chickens so love. I just mix some of their regular crumble with water, to the consistency of clumpy wet sand. They flock to it like it's a treat! I only give them as much as they'll eat within a couple of hours though, and haven't had any problems with it molding in the summer or freezing in the winter. It's gone before any of that happens.
And then my main feeder is a large 5 gallon DIY bucket feeder that stays inside the coop. I only have 7 chickens, so when I fill it up, it lasts for quite a while. Especially because they also eat their mash outside. I've never had any problems with it, in any weather, and we have the full range of weather - really hot, really cold, really humid, really dry etc. throughout the year.