It was a number of years ago now and I can't quite recall the exact circumstances but there was a period of time when Spotify limited the number of artists/albums I could save to my Library. Maybe I was on a free account at the time? I dunno...
Anyway, artists and albums were limited but individually liked songs had no limit. So as a work around, if I came across an album I wanted to save, I'd just like all the tracks individually.
Whatever the original reason behind the artist/album limit, I now no longer have a limit and my attention has turned to my Likes playlist which has become rather unwieldy like an abandoned overgrown garden.
Sticking the playlist on in the car is a gamble. Sometimes I'll get tracks that belong on there but I'm finding myself skipping most tracks so I've decided now is the time to reclaim the playlist and only have tracks on there that I feel really ought to be.
It's not a quick job, there are currently over 4000 tracks in there but hopefully with a few clean-up sessions, I'll be back to listening to music in the car rather than hitting the skip button.
Update: I've finished going through the playlist and removed the vast majority of tracks (but saved the albums to my library). There are now just over 400 songs in my Likes playlist but these are songs I've actively chosen to be there now. Next task will be to listen to music and start building the list up again.