What is the maximum number of Apple TV that can use itunes?

I have iTunes (12.4.1.6) running on windows with a total of 6 Apple TV. According to various Apple posts, you are permitted 10 associations of which 5 can be computers. At most, i can get the iTunes server and 5 apple TV working concurrently. I've repeated the exercise, the first 5 ATV accessing the library work, #6 does not.

Related question #1, does the apple remote app running on an a iOS device count in the total? For this test, i have no remotes configured.

Related question #2, How can you see ALL devices using a particular id? The obvious manage devices for Apple ID does not show things like ATV.
Can someone elaborate on the constraint here and how to view all associations?