radioman148, in the 1960s and early 1970s, when DJs like John Landecker (as Dow Jones in 1966), Jim Hampton, Bill Hennes (later at WMAQ) (at WTRX he was John Paul Jones), and George Stagg/Allan Stagg (WLS and various 94.7 entities), were spinning records at WTRX Flint, MI, they were playing songs as much as thirteen weeks before WLS played them! So we even had the some of the same DJs breaking the records WLS refused to play! At least until they were ready for the recurrent bin everywhere else.
When I was studying at the University of Michigan, I propped a portable radio up against a drain pipe in a building (for nearly fade free reception) one evening in 1976, and heard John Landecker play "Play That Funky Music" every 46 minutes on WLS for the entire shift. Locals and nearby markets, like you say, had signed off, reduced power, changed patterns, or were interfered with except during Auroral groundwave conditions.