In the 60's, backselling of either the set or the song was common. Once Shulke and Bonneville dominated the genre by the very early 70's, the backsell was eliminated or reduced.This is an unidentified reel-to-reel recording posted to YT that I've ID'ed as WDBN Medina, Ohio from January 29, 1975. What's most fascinating to me is that all the songs are backsold. Most vintage EZL/BM airchecks and surviving stations are simply jukeboxes. Did many stations do this sort of backselling of the songs?
The first Beautiful Music station I owned went on the air in 1966. We never did backsells. Too much talk, and we depended on in-store and restaurant listening for promote the brand and the band (first FM in the market). I ran the format in the 70's in several places, and never backsold. I syndicated the format for much of the 80's and our stations... over 80 at one point... did not backsell..