All I know is I did 8 years long haul with EK. And at the end I was completely burnt out. I stopped flying because I realised that I was in my early 50s and trying to keep it up was getting simply impossible. It took me 6 months after I stopped flying to realise just how tired I had been.. that I lived in a world of constant fatigue that I had come to accept as ‘ normal’. I know I feel so much better not flying now. ( 35 years and 22000 hours when I stopped.). Long haul flying.. when the limits are used as targets, IMHO will take years off your life.