If the user needs access to a file that is owned by another user, it should be stored in a common access area.

Define "common access". Execute permission on the directory is enough, because all that's needed in finding the inode number given the file name:

$ id -u
1500
$ id -g
1000
$ ls -ld Foo
drwx--x--x  2 root root 4096 May 13 08:54 Foo
$ cat Foo/bar
Hello, world!
$ sudo ls -l Foo
total 4
-rw-r--r--  1 root root 13 May 13 08:55 bar
$
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In fact, there are some security related functions (of which SSH is one) that refuse to run if the user's home directory is world readable.

Yes, and penguins are black and white. How does that relate to using file ACLs?