Another important factor is that some authors write more than one best-selling book. In fact, I’d expect all the lists to have a lot of repeat authors. Just looking at the current New York Times hardcover fiction list I see James Patterson, Danielle Steele, Elizabeth Strout, Kristin Hannah, Melanie Benjamin, John Grisham, Nicholas Sparks, Stuart Woods, Harper Lee and Tami Hoag. All of them have written NYT bestsellers before, so at least 10 of the top 16 on that list are repeats.