Well, no, nobody wins every year. But Lois McMaster Bujold is about as close as you can get. Very few people walk away with more than one or two Best Novel awards, this being the Big One. In fact, if you look at the list, it’s Robert A. Heinlein, Lois McMaster Bujold, Isaac Asimov, Connie Willis, and Vernor Vinge (at 5, 4, 3, 3, 3). Given the percentage of female writers in the early days, this is a pretty good showing, all-told, especially, if you ignore retro Hugos (when it becomes 4, 4, 2, 3, 3).