From the filesystem hierarchy standard, /usr/local would be for "local data, specific to this host." But I don't quite understand that, since isn't the entire filesystem usually local to the host? i.e. /bin contains binaries, and those binary files will only be used to invoke processes on this host, generally speaking. A second host would have its own copy of binaries, though they might actually be the same if you diffed them.
So, can you explain the meaning of "local data"? In what sense is it local?