Quite often customers want to organize their classical music by Composer rather than Album Artist - see Renaming music by genre
The main difficulty with this approach is that if an album contains works by different composers then the composer value is not the same for all tracks and the album can be split into different folders.
To address this issue I am working on a new Album Composer field that typically contains any composer listed for any tracks on an album, and importantly is guaranteed to be the same for all tracks on an album. This mean it can then be used in conjuction with Is Classical field to organize Classical albums by Composer(s) without the risk of breaking up tracks of the album.
We are not basing on directly on MusicBrainz composers but after the composers have been added to each song because for classical we sometimes to have to do clever stuff to work out the song composers since they do not necessarily coming from a composer relation within MusicBrainz.
Also if the majority of tracks are by one composer and just have the odd tracks by another composer then we just stick with main composer, so the rule is we only add composer if they are credited as composer on at least two tracks unless there is no composer on more than one track , because what we typically want to capture is a classical release with two works with each work by different composer so Album Composer field ends up with two composers, this is the typical usecase. Also I think if there are more than x composers Album Composer should just be set to Various Artists to avoid a long list, I was thinking x should be 5
I’m open to suggestions on adjustments to this approach.