I do that with a currently similar size library, although a fair chunk of that is new so maybe more like 5-8k songs that I've usually been listening to, mostly in albums. Maybe more repetition than you, particularly when I first get an album (for me there is a "burn this album or song into my memory" aspect of repetition), but I often pick out an album or artist I'm in the mood for and haven't heard for a while. For me it is mostly FLAC files that I play with mpv, organized in directories by artist and album (often shortened to easily type, in the /a directory). I think many people don't like albums for some reason but for those of us that do it much easier to pick a few albums to play than to pick a bunch of random songs. Of course, more people used to do this out of necessecity when music was mostly distributed by CDs or records, so it may partly depend on age as well how often people do that and for the people who don't like albums it was a relief to be able to easily make playlists or pick randomly from all songs. I have a few playlists that I've made but not many, although I have been thinking that I should make a few more (partly because I have a bunch of songs that aren't in any album, although I also often listen to everything I have from a particular artist). I've been trying to do more of a mixtape thing, matching the music and getting the right amount of silence between tracks. The few playlists I have I think of as just another album.
I do keep most game music separate since that tends to be short and have excessive repetition, although the few games with music that stands on its own I put in my general collection. I'm also working on creating an alternative tree with volume normalized opus files, but I still have a ways to go.
I've always had a better memory for music than most things and can play a bunch of music in my head fairly well, never complete songs but maybe up to a minute or two with quite a bit of detail (and usually but not always accurately :/). From various threads, it sounds like a lot of people can't do that. Although it is also mostly as I happen to think of it, intentionally recalling particular music is harder and takes some time (and depends on how long it has been since I heard it). I have some challenges with memory in general due to health issues but can still pick out the albums I'd like to hear from memory fairly well.