 But sometimes advertisers back out, or end up going with smaller ads, or miss a deadline, or the magazine ends up with extra content, all of which creates an opportunity for another advertiser who can come in at the last minute.Radio is one of the best media for remnant buys because—unlike print media which can be expanded and contracted to a certain extent as needed—radio advertising is finite.There are a fixed number of spots in one hour that must be filled.