Train your chickens to come when called, so you can let them out and get them in anytime you want. Also enables you to call them to safety when predators lurk. If you have multiple flocks, you can train each to come to a different call. Very helpful when you have new pullets free ranging with old flock, and need to get each flock to its own coop.
Our chickens in their DIY chicken tunnel. We live in a residential area, so to keep the chickens protected from hawks, dogs and other predators (and to keep them out of our neighbor's yard) we hook up their portable play-pen to the run and let them range.