If you haven’t seen it before, it’s new. Or at least new to you. And that’s good enough. Increasingly, that seems to be the motto when it comes to musical performances on late-night TV, as more and more shows parcel out songs over the course of days or even weeks. Of the major network players, nobody does it more often and more blatantly than The Late Show With Stephen Colbert. Look no further than recent appearances by BTS and Bonnie Raitt — or Thursday night’s performance of Rylan by The National, clearly the second chunk of a segment they taped more than a week ago, before their album I Am Easy to Find was released. It wasn’t the only dated offering on tap: Last Call With Carson Daly also dredged up two more songs from a Durand Jones and the Indications gig they started airing back in early April. Oh well. On the plus side, they were both superior to the more timely tunes being broadcast: Electro-popster Bazzi’s performance of Paradise on The Tonight Show Starring Jimmy Fallon (bet his Fleet Week audience was thrilled) and Ben Platt’s folk-popish ballad Grow As We Go on Jimmy Kimmel Live. Or as close to live as anything gets these days, it seems.