This has been on my mind for years now:
Why do most radio stations insist on playing the same selection of songs over and over?
I imagine it must be a copyrights thing? Pay for usage of this particular catalogue for a year?
Don’t those DJs get absolutely sick of it after a while?
Radio playlists are a science like marketing. Half the budget is wasted, you're just never sure which half.
Stations have a target audience. They will have focused grouped this. They know their favorite music, how long on average they listen, and how much they will expect to hear certain artists. The DJs are mere announcers, they have little to no choice in what they play, and they are grateful to have a job. So like anybody working in retail during Christmas, they can tune out the music in their heads.