Both The Voice and American Idol are diluting the product, or stretching the inventory, tonight with retrospective specials. In the case of The Voice, it’s a one-hour “previously on The Voice” special, catching up viewers on what’s happened so far this season. And since Cycle 10 has been, to this point, the show’s best, I’d suggest it for anyone who hasn’t been watching, but would like to jump aboard the bandwagon. And in this case, the band is included.