Part of the trouble is that a small coop is still small, no matter how few chickens it has.
So true!
It's cool you had a link to those old studies.
One thing I found most limiting is roost space. In a small coop it is hard to have enough roost (1 ft each) and still provide room for them to jump down clear of each other.
I confess, I violate the minimum footage standard.
But, I selected heavily for docile birds.
Their door opens at dawn, and their yard is big with woods and an open area. Those things help me get away with it.
But, I had to be very creative with roost placement to fit three 2x4s in and still allow them an easy landing zone.
I also watch temperaments and have other quarters for hormonal broodies, etc. I've rehomed hens merely for the way they act in the flock. Most of mine lay together in the woods most of the day, when they're not running around or snacking.
As well, we have lots of ventilation. Which is a limiting factor for OP, whose other recent thread shows issues with humidity due to the design of the cupola and their weather. I think in that thread we all thought the coop was a lot bigger from the interior photo. It makes more sense now.
