What is interesting looking at some of the aircraft are the similar duration flights some of the aircraft fly.
If you follow one of the 747's - it seems to fly to only Hong Kong and Los Angeles - two routes which are similar in length.
Likewise with some of the 777's - one flew to Newark, Philadelphia, Lagos, Kuwait and Dubai all in a week. Again arguably similar length routes.
I would have thought they would have wanted to mix the lengths of sectors up a little for engine wear purposes, etc ?