Carlsen plays lines that his opponent will not have looked at, that is as far as his 'preparation' extends. He played the Ponziani against Harikrishna in Wijk 2013 for goodness sake, nobody prepares anything against that.
You miss the point.
The point I was making was Magnus Carlsen has some of the best opening study/preparation in the world.
Harikrishna would not be able to prepare against Magnus in the Ponziani because he wouldn't know Magnus is even playing it against him!
The "person" who is doing the preparation is "Magnus".
The Ponziani opening is not considered one of the greatest chess lines.
Which means Magnus would have to do extreme preparation when playing it.
We will just have to agree to disagree, Carlsen doesn't get involved in any theoretical battles in main line openings because he doesn't want to be surprised by a novelty from his opponent. Throwing out the Ponziani is a good choice in this case because there haven't been any critical novelties in that opening for a hundred years! They followed a game from 1965 up to move 8 but I would doubt if either of them actually knew that at the time. The same goes for his quiet double fianchetto openings with White, there aren't any variations where Black can blow the position open and play for an advantage, its all about manouevring and keeping control of the position with the view to squeezing out a small plus in the endgame.
White is always 1 move ahead. And he gets extra clock time for first move.