It's great to separate out audio files in a Working File as deep as you can. More is always better.

For example, have kicks separate from snares, separate from hats is great if you can do it. Beyond that, separating out individual voices of harmony parts is ideal. And if you can split out multiple mics on a drum kit, that's excellent. 

If your musical contribution is in the form of a big set of tracks (like a full song), then it can also be helpful to include stems (AKA sub-mixes) in your working file along with the individual tracks: Groupings of tracks like “drums”, “guitars”, “strings” “BKG Vox”, etc. Stems can make it easier for people on smaller systems to work with your tracks, and stems will also keep your balances and effects intact for remixers who don’t intend to change them. And they make it easy for anyone to assemble a “mix minus vocal," for example.

Keep in mind that Working Files are not mandatory, but are highly recommended so others can more easily remix your audio contributions.