Oh man.... you can squeeze those little guys and gals into some small spaces. I kept up to 5 in a 16" x 16" cage for breeding (4 hens and a roo). The girls all laid regularly and when I hatched 20 eggs I was rewarded with 14 chicks!
Any bird can live in a tight space. It's just not the most humane way to do it or the cleanest way to do it. If you think about it, the chicken eggs you buy at the store are often in 8" x 16" cages with a cup of water and a trough of feed in front of them. They don't even get to turn around. Yet they live their lives putting out an egg a day for Mc Muffins or the local church's egg bake.