If you have e.g. a "biff" album by "foo" with a track by "foo feat. bar" then it will by default be saved in `/foo/biff/01 foo feat. bar - title`.

In order to prevent artist directory fragmentation, if you have a NAT track by "foo feat. bar" you would want this to be saved as e.g. `/foo/foo feat. bar - title` rather than `/foo feat. bar/foo feat. bar - title`.