I don't think anyone would object to a very long list. Kieron Gillen maintains one for his comic The Wicked and the Divine and it has nearly five hundred. They may not listen to it all in one go, but unless you're trying to make a concept album of it, they don't need to.

Similarly, I keep playlists for the game I'm making and each of its characters. The character lists top out around 12 currently 'cause they're specific and I try to keep them fairly even with each other so everyone's favorite is equally represented. The general list has no limit, but I also keep future characters' songs in there until I debut them so its count fluctuates.