Depends on what you consider chess-related work. I would put sleep, exercise, diet, meditation and other interests as chess-related work for a full-time chess p

Depends on what you consider chess-related work. I would put sleep, exercise, diet, meditation and other interests as chess-related work for a full-time chess player. Even if you didn't, studying chess for more than 8 hours a day has diminishing returns, especially for older players like Carlsen. One of the reasons older players don't continue to get better and start to get worse as they pass 40 is they find it hard to maintain high levels of concentration over a 4 hour game.