Looking deeply into the past
I seem to remember an instructor when I did my ATPL way back discussing range / endurance when he was a nav on Bristol Brittanias.
Seemed a suggestion was made to BOAC that three engine holding or long range cruise gave dramatic decreases in fuel consumption with corresponding increase in range / endurance. Don't Nimrods and Orions do similar (shut down two) in their various roles?
Seeing one engine stopped might spook a few passengers, but that's never bothered anybody before!!
Seem to remember something about a concept business jet with two engines of differing power output designe dto have both running for T/o or landing but only one operating in cruise.
Just some ramblings from a dinosaur.