When we had 25 cats, (well around that number) they did used to spray sometimes. But because a lot of them arrrived in litters of kittens, they always stayed friendly. The ones that arrived as older single cats used to have more of a problem. But you are also right in that our house was large, and we had acreage, so they all had their own little hang out areas. Thats a very cute picture you posted, they seem pretty happy.
25 cats! That must have been interesting.
Those were happier times in the photo, we've had issues recently because of outsiders as well :(