W-e - Going to SIN via FRA is fine; coming back here e-w causes jet lag.
That said, the best flight in my life was UA F from FO to SYD night flight left 11 PM (2AM my time after a long day) - slept like a (good) baby and no jet lag.v The return was one of the worst jet lags - AM flight.
I am beginning to think it is the time the flight starts that matters. If it is a long AM flight that causes jet lag.
Long flights at night when sound asleep causes no jet lag.
Watching movies worsens jet lag - alcohol has no effect (may be on me alone)