I disagree.
I was in Southern California last September driving around and listening to KRTH for random 15-30 minute segments over a 3-5 day period (not consecutively) and I heard several songs repeat during the times I tuned in. And yes, "Hotel California", "Go Your Own Way" and "Girls Just Wanna Have Fun", to name a few. I tuned out and changed stations.
I think your assessment may have applied when stations were playing songs just twice a day, but five times a day, you are likely to hear that song more than once in 14-21 days, no matter when you tune in.
Right. But how many times a day did you punch into KRTH? If it was more than twice, it was likely more than the typical KRTH listener. Again, remember, they're sharing him or her listening time with five or six other radio stations, and they've got him or her for 15 minutes tops. And as David91326 illustrates, if they're your favorite songs, hearing them every day is fine. As we've said before, what's worse is not hearing them enough---that's where a listener begins to think that your station isn't really in tune with what they want to hear.