Hmmm... for me, when (for example) I'm mastering from stems, or exporiting stems for a live shows, it's more like:

bass (all the tracks that function as a bass)

drums (all the drums tracks)

keys

synths

strings

guitars

backvocals

vocals

bagpipes (all the bagpipes of the world one can fit into a track)

....

but often it's just bass, drums, guitars, vocals, the rest