Primary artist for [track 10 of this release](http://musicbrainz.org/release/3c9e7a42-1d49-4ba7-86ec-d8aaf6f39f2e) which is that recording would be [Le Yan](http://musicbrainz.org/artist/1ff694dc-6b7a-4fdb-b52f-aed021e983a7) i.e. the first named artist. So, if the album would be in `/Chinese Man/The Groove Sessions, Volume 3` then...

1. under existing default naming script the NAT would be in `/Le Yan & Tomapam feat. Cyph4/[Non-Album Tracks]`
2. using %_primaryartist% of my proposed default naming script, the NAT would be in `/Le Yan`
3. using %artist% instead it would be in `/Le Yan & Tomapam feat. Cyph4`

I am beginning to see why my proposed use of %_primaryartist% is not so useful, and that (thanks to insightful examples from @zas) there is not really any perfect solution. So, I now propose to drop both %_primaryartist% and its use in the default naming script.