Mine are about 12 weeks old and do the exact same thing.
I have one 2x4 roost that extends the entire width of the coop about 4ft high and another lower one going across the side wall.
The chickens want to bunch up at the end of the roost (closest to the door) and they'll walk over/under each other to get that prime spot.
Sometimes they knock each other off the roost. (There is a smaller bunch at the other end of the roost, but they seem more civilized.)
They do finally settle down.
I've sat inside the coop and watched this go on for about 20 minutes.
Then on the floor of the coop I have several Tidy Cat litter boxes and the "bottom dwellers" (about 10 of 'em) all seem to want to squeeze into ONE of the boxes.
One evening during the bottom-dwellers' squabbling, I VERY GENTLY slid the "preferred" box (full of chickens) away from the wall and slid the empty one in its place.
The ones that woke up and came out of the box couldn't figure out which box to go back to.
I honestly cannot figure out how so many chickens can fit inside one Tidy Cat litter box!
Chickens are just so funny to watch!!!