Just a little anecdotal evidence from the last time I was really paying much attention to music on the radio… a few years ago, mostly new country stations in the golden horseshoe area of ontario…
though almost all of the time they’d play recent singles or golden oldies… (at least I assume singles… I could almost never find actual ‘singles’ in the record stores, but specific tracks that seemed to be getting ‘released’ for radio at a specified time and would often have a video out around the same time…) occasionally there would be a more obscure cut from an album that would not get played much again. Also, occasionally as part of a special promotion for the release of a new album by a big name star, a particular station would set a time and play the entire thing through, along with commentary and sound bites from the artist.
(wanders away humming to himself.)