What people have, what actually works well for them and what will work for you could be very different things.
Common 'rule of thumb' is 10 sqft per bird in the run and 4 sqft in the coop, which is a minimum for confined birds, IMO.
I wanted more birds, but learned the first winter that my space is just not going to allow it....
.......for both the birds well being and regarding certain maintenance aspects.
It also can be highly dependent on your climate and whether you can free range year round.
Heavy snow accumulation can drastically reduce your birds space, most birds do not like to wander on the snowpack, unless you have a large run with a solid roof.