What happens when a redeye (cross country) flight has a nice 150 kt tailwind from LAX to JFK and makes the journey quickly? Do airlines:
A - Take advantage of the faster speed, arriving at a very early hour?
B - Cut back power for fuel savings to maintain the same groundspeed, saving the airline fuel costs, with the idea that neither equipment nor pax needs to be in NYC at 4 am?
Seriously I could see "B" being chosen.
BTW, interesting to compare redeyes in Australia and the U.S.:
PER-SYD 1140p - 640a (4h 00m) USD$311 (Dec 18)
LAX-EWR 1035p - 640a (5h 05m) USD$1075 (Dec 18)