Question: Why do record labels have songs play on the radio months before the CD is available to buy? It's odd because I'll hear the song and I want to buy it, but by the time it's for sale I'm tired of it and don't buy it.  What is the logic of playing the song to death before it's available in stores?

Answer: to ensure that the song is recognisable by the time that they release the cd. If they releases both at the same time, it would still take a bit of time for sales to pick up as people would  not be familiar with the songs.
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