I am 46 and my prime for rabid devotion to music peaked with mid to late 80's Metal (not Thrash, it sucked). This is my observation: back then, any genre of music was TOTALLY played to death; u got sick of it just like now. Where I am going with this is that even the classic rock, country, etc. now play the same songs from then over, and over, and over squared to one-thousand-million. I know for a fact, playing guitar and having many musician friends in the past, that there are KILLER songs that you never hear once. I theorize that if a station were not to play the same song twice, the turnaround would be one month. That is very conserativ, with all the music out there - past especially, and present - it would likely be months. Speaking from experience: it doesn't change and it certainly SUCKS!