It's possible, of course, that Carlsen HAS been working hard on opening preparation, and has amassed a whole library of novelties... and that he's saving them all for the World Championship cycle.
Remember that Fischer found a crushing novelty in the Petroff, and saved it for years, hoping to spring it on Petrosian or Karpov in a Candidates match (both of them are known Petroff players).
Hello chess fan's, just a thought how long be you think it will be world champ and what part of his game is there a weakness......