Fatty
The rub is the combination of duty in time combined with number of pilots on certain sector lengths and layover time.
My previous carrier, a long hauler, had minus 1 hour BUT anything over 8hrs - 3 pilots, anything over 11hrs - 4 pilots. And of course all ULRs had a minimum of 36 HR layovers (90% 48h) An acceptable balance.
If we were T -minus 90 here a lot of those grueling Asian returns, long day/night turns ETC would mandate an extra relief pilot.
It's just always pushing the envelope with manning and layover length that is burning the guys out.
It's a cheese hole.