Another option there might be that certain commercial timings emerge more or less naturally from the constraints on the problem. If radio stations schedule time blocks by hours or some 1/n division of hours, for example, there's going to be a break between segments at every N:00 -- a natural place to put commercials.

This would be a Schelling point, except that I doubt most radio stations think of commercial timing relative to other stations in terms of game-theoretic advantage.