The timing of the door closing (and opening) can be changed when using a timer, and the light sensor can be adjusted to close earlier or later with different levels of light. I have only ONCE had one ninny of a chicken locked out, and I've been using these doors for nearly two years.
At the factory setting for the light sensor, all of my chickens are well-roosted. Even the juvenile chickens, the "tween-agers," which tend to stay outside longer than their fuddy-duddy grown up flock members, are inside before the door closes. Most of them are clamoring to be let out in the morning as it begins to rise to allow them out of the coop.
But yes, it has happened when one of my less intelligent pullets got very involved in digging in a once-planted planter for bugs, under the porch light, for a long time. By the time she finished farting around in that planter, the door had closed. She settled down into the planter and just roosted there until I found her (doing the nightly head count and coming up one bird short). I picked her up and carried her to the coop, then put her into it through the people door.
Your mileage may vary.
