Quote "Couple of years ago I flew from Heathrow, to Kansai, to Cairns, to Port Moresby, to Goroka. That was a shade under 36 hours end-to-end."
I think that is a valid response to the original question about world’s most grueling flight. Bloke was trying to get from London to Goroka in PNG. No direct connection but still a continuous journey from one destination to another. Not muck around going back and forwards.