A notable pattern that developed during the 2000s has been for certain pop songs to have lengthy runs on the Hot Adult Contemporary Tracks chart, even after the songs have fallen off the Hot 100. Songs such as "Love Story" and "You Belong with Me" by Taylor Swift, "Waiting on the World to Change" by John Mayer, "Love Song" by Sara Bareilles and "You're Beautiful" by James Blunt have remained on the AC chart for many weeks, in some cases over a year after the song was originally released. An article on MTV's website by Corey Moss describes this trend: "In other words, AC stations are where pop songs go to die a very long death. Or, to optimists, to get a second life." One theory states that many adult contemporary stations play less newer music because they also give ample airtime to hits of the past, so the de-emphasis on new songs slows the progression of the AC chart. Also, certain program directors have asserted that AC is a song-based format, as opposed to other radio formats that are infused with singer-based programming, so there is no guarantee that a new single by a certain artist will appeal to the listeners.