Protecting grass in animal pens

Corvus

Tiller

I saw some YouTuber advise that if you put down grass starter (or have a handy tuft) then put a fence post atop it, it will be protected from being eaten and propagate into the area where the critters can get to it. I tried that on the perimeter fence and it didn’t propagate on either side of the fence line. Was there a change in an update, would it work with a solitary post, or was the guy just flat wrong?
While I am on the subject, I’m hazy on the animal doors. Sometimes with the coop, if I’m a bit slow getting to it, when I open it the chickens come out and scatter like quail (I need to record my running around trying to pet them all). Other times they’re already outside with the door still closed. Can they work latches or was one trapped outside the night before? And what’s the best time to roll the door down? “Didn’t make it back? It’s outside all night for you, chickie!”

While I am on the subject, I’m hazy on the animal doors. Sometimes with the coop, if I’m a bit slow getting to it, when I open it the chickens come out and scatter like quail (I need to record my running around trying to pet them all). Other times they’re already outside with the door still closed. Can they work latches