When I was in college radio, 1974-78, records vinyl format, demos were albums, not 45s, with DJ discretion in choosing what selections to play, all items played set down in logbook. Presumably, frequency of play determined what cuts would be on formally released record that followed.

Since Blackout has already been released, what purpose is served by 'holding back' individual cuts from being played on radio stations? Why not just send entire CD out to music directors to choose whatever they want, or just send out all cuts as individual CDs and be done with it?