Fatigue management - hinted at, but not specifically mentioned, is the obligation on the pilots flying to comply with the intent of the program,- that is, to utilise the available facilities to rest during the middle part of the day.
Human Factors tells us that this a long term practical reality, both from the dicipline required to undertake the rest period, and the impossibility of resetting the circadian rhythms to achieve quality rest.
There will always be those who adapt to the requirements, and also those who lack the ability to adapt (for whatever reason), and have their "eyes hanging out" as a consequence.
Personally, I have a lot of respect for the operation, and for the aircraft. As for wing separations, most of those were due to earlier incarnations of the engineering resulting in +ve G loadings overcoming a weakened centre structure, and a low percentage attributed purely to flight velocity induced loadings resulting in -ve G symetrical failures at the inboard ends of the ailerons.
Tite