“If you do not realise this, and assume that everyone who says they are working eight hours per day actually is, you are probably going to wreck your mental health trying to keep up with them.”
MacIver gets one to two hours of hard thinking done on most days, and rarely four. That is normal. The eight-hour day is a lie everyone repeats about everyone else. Managers who believe it burn out the people who try to live up to it.