Don't chickens go into kind of a stupor at night when they fall asleep. I was told that was the best time to introduce new chickens into the flock, where everyone else was asleep. So why leave the door open all night???
With all the time, money & effort invested in your chickens, why take a chance by leaving the door open. Sometimes I can not get to my chickens till 9 am, I put fresh food & water out for them in their coop, when I close them up for the night, they are in their roost & do not come down to eat it. I just get the weird look from them, like "Hey we are trying to sleep here, just close the door & leave!" My chickens are at the door waiting for me to open it for them in the morning, but no issues or fighting. I usually let them out by 7:30am, then have to explain to them that "Yes I know you want to be out & free ranging, but you have to wait till Bethie comes home from school. Then I will let you out."
My youngest is in Pre-K and gets home by 11:45 am, then I am home the rest of the day & can watch the chickens as they free range.
My neighbor I found out yesterday, would leave her coop door open at night. She has 3 dogs who will go after anything that does not belong in their yard. Never bothered the chickens, until a coon came, got into the coop and killed a couple of her hens. A few days later, her dog got into the run, and killed the rest of her flock.
I am in the process now of winterizing my coop & making sure everything is secure. The only way anything could get into my coop, is if they broke the glass window (safety glass). With the drought we have had here in Texas, there are so many animals out & about looking for food & water. See way too many road kill on the roads this last month, so I am being over cautious with my chickens.
Just remember, we are their protectors, they have no defenses against coons, weasels, possums, foxes, or dogs but us. Get an automatic door if you can't get up early enough. Make more ventilation of you want them to have fresh air. But please keep the doors closed at night.
No one wants to wake up to dead chickens in the morning. JMHO