WRH
Clearly, you have never seen a computer flight plan for an overwater leg. It is all spelled out for CPs--depressurization, OEI and medical diversions. Fuel burn to CP, Fuel remaining, drift down plan, distances, winds, times and fuel remaining, all planning required. NOBODY coasts out on a guess. I've done many legs with, as many 9 critical points on a CFP by Jeppesen. Petro to Tahiti is one, Honolulu to Koror is another.
In corporate, we don't "stay up and get the fuel burn", we descend to FL100 and divert, as planned. Yes, we have good oxygen supply, but I don't wish to expose the passengers to using oxygen out of constant flow masks for hours, nor expose them to physiological problems at high altitude. Having crossed to HI at lower levels there is no likelihood of problems at FL100
As usual, you are posting your ignorance of airline, military, corporate operations and apathy as to learning more. In military, airline and corporate, I've used reduced power, on condition maintenance, the list goes one, all very successfully.
GF