We see that repetition not only in radio but TV. It is not rare for a cable TV channel to play a movie over and over or a block of TV shows over and over.
CNN Headline News was on a 30 minute repeat. I recall the rival 'give us 22 minutes, we give you the world'
In Top 40's heyday there were stations with tiny playlists that pretty much repeated everything but the recurrents every 70 minutes. A friend of mine and I were talking about the listening patterns and wondered about a 100% hot hits station that repeated the currents about every 30 or 40 minutes.
I recalled something Todd Storz said: after customers played the same songs over and over all day, the employees, after the customers were gone and they were cleaning up, selected the same songs their customers did on the jukebox to listen to while they cleaned up.
I can see a pattern on talk shows of repeating the same material. Everybody talks about the same topics, host after host, all day into the night.
Sort of off topic, but those of us on air before PPM played the Arbitron clock, taught there are more listeners in the 1st and 3rd quarter hours than in the 2nd and 4th. (and sweeping the quarter hours for that paper credit). Did PPM change that thinking?