Someone asked me, and I'm compelled to answer. Many radio stations
work off of a "playlist", or set of songs or artists that the
station wants to emphasize. Even with the "classic rock" format
or the "album oriented rock" format of the past few decades,
you'll notice that some stations seem to get into a Jethro Tull
or Electric Light Orchestra rut for a few days. It's the playlist
The songs or artists that get the most play are in "heavy rotation."
In my case, it's more of a pun, because I rarely listen to the radio
outside of news or sports requirements, and my music is piped from
iPod or CD - heavy rotation of another kind.