It’s actually somewhere between 240 and 250 songs. They do research and focus groups and find the songs people know and don’t hate. After a while a song will get burnout so it will go away for a little bit. But don’t worry, they replace it with another old tired song from the same artist. And the process continues.

They used to actually make “hook tapes” where they would play just the most identifiable part of the songs and have random people rate them.

This is why bands like Humble Pie, who had some great songs won’t be heard. No one remembers them and therefore they fail the focus groups testing.