This is more thinking out loud than a precise idea…
I have some radio plays or audiobooks ripped from CD, and many come on multiple CDs, sometimes like 12 discs with 15 tracks each. I tag those tracks with one album title (e.g. album “Radioplay Xyz” for all discs, not “Radiopla Xyz [Disc 1]” like you see sometimes). I also tag the disc number properly. So when I select the album in Symfonium (or any other player), I have a long list of 180 tracks, but usually don’t want to play more than one disc worth of tracks.
What would be convenient now is if there was a header for each disc between the tracks (when sorted by track number), and that header had its own three dots menu to select all the tracks of that disc for playback or adding to a playlist.
Apart from the programmatic problem of selecting the tracks, this probably would need elegant UI design. But it would be a really cool feature