I think people get too hung up on how much space their hens need. The little backyard coop I purchased recommended different numbers depending on the type (bantams, standards or large breeds), if they would be free ranging or have access to a run. The coop I purchased recommended 5 to 6 standards,10 if one added additional run space. The roost area of my coop is only 3'x 3' and has 2 roosts 12 inches apart. I've added run space, my 5 hens have almost 100 sq ft. I could easily add another 3 to 5 hens. My chickens only enter the roost area to roost at night or get access to the nesting boxes during the day.
Not sure how you would fit 10 hens on 6' of roost. They might squeak in the winter when they stay close to be warmer but they will want to spread out in warmer weather. They have a really hard time taking their coats off at bedtime