This discussion doesn't take into account the kind of controls that Clear Channel and other corporately owned stations no normally excercise over what is played normally, which is total--DJ receive a list of what they are to play that has been generated by a computer program which prioritizes songs based on market research that has determine how the station's target audience will respond to them. Most stations are what is called "narrowcast" which is to say that they have a very narrow range of artists and recording styles that they play, regardless of what is "popular"--The format always dictates what will or will not be played--Even the seemingly wild and crazy "Shock Jocks" don't have much say in what they play--

There is another factor here--all stations have a list of commercials, recordings, announcements, and even certain kinds of feature/news items that are to be immediately blacked out when certain events occur--airline commercials, for instance, are immediately pulled, as a routine matter, when there is a plane crash--this is all business as usual--