I don't know what kinds of weather you get there, but over here we can get a lot of snow, high winds and subzero temps here that can last a couple of weeks up to, or beyond, a couple of months. Even with covered runs, a lot of chickens will want to huddle into the coop for a place out of the wind, blowing snow or just for warmth, so we don't often count adequate run space as being a trade off for insufficient coop space.
Usually we err on the side of too much space rather than too little when considering possible confinement due to inclement weather. It's also during that kind of weather when illness can be more prevalent, so too many birds confined in too small of spaces during rough weather is a recipe for trouble. Then there is the factor of overcrowding during those times causing stress and subsequent social problems like bullying, feather picking, cannibalism, etc.
So, when someone asks "how many hens can I keep" in X amount of space, I often err on the side of caution. I read an awful lot of posts at this time of year about illness, bullying, feather picking and cannibalism and a huge number of those posts can be attributed to lack of adequate space for the number of hens being kept.