If the posts of Woodja51 (#2199) and Weapons Hot(#2205) turn out to be on the mark, then it would show a major flaw in the “Cruise Captain” concept for long haul flights. In fact, in many airlines, cruise captains have almost zero experience of manual flight from the left hand seat, and that manual flight experience would very likely be only in the simulator.
Perhaps at the time of dividing up and allocating “on seat” and “rest” periods among the pilots for the flight, that part of the flight which eventually proved to be most critical was not considered to be likely to be the most challenging.