I know I am a licensed pilot, and can read both Continental (Lycoming is the same) and Cessna's docs, and with both, you are told to generally avoid full RPM/throttle other than takeoff . . . and I trust them a lot more than these derps . . . (who I also note are from the eperimemtal world, where some things are viewed differently . . . I'm talking amout commercially produced aircraft, whether it be jet, turboprop, or piston . . . and even if the claims are true for the engine alone, youmdom't fly just the engine, you fly the entire aircraft where,
again, due to air resistance, etc. you dom't get best fuel economy at higher speed . . . the physics says so.
Then there is the minor little detail that purported "efficiency" is largely irrelevant in power equipment, since you can't seriously be saying that a machine that can do a job at say, 2400 RPM and part throttle will burn more fuel than running wide open, at who knows what speed? (The typical 3600 still isn't wide open, it's governed . . .true "wide open" would likely overrev and blow it . . .) So, it's really comes down to part throttle vs. part throttle, and I find it comical at best to claim the superiority of one over the other . . .
I stand by my statement (and published docs) that non adjustable throttles are in the same category as limiter caps . . . EPA mandates that have *ZERO* to do with use cases! And, why do folks always seem to duck the point that EFI engines, with thier far more accurate metering and ability to meet emissions over a far wider range of settings, don't seem to have this restriction, rather tending to have full throttle control. If the argument thr full speeders are making is true, induction system type should benirrelevant, hut it appears to not be the case either . . .