Interesting and thoughtful article. Most of my experience is with older performance cars, but it gives me a slightly different opinion on the matter, at least at high speeds. And really, I might be wrong when it comes to modern cars, but here’s my understanding (please feel free to comment and/or disagree):

First, engines are cooled by circulating coolant (anti-freeze and/or water) that undergoes radiant cooling. Radiant cooling occurs when air is moved rapidly through the radiator containing the coolant. The air might be pulled through by the fan, pushed through by displacement of a moving car, or both if the car is moving at slow speeds.

At high speeds, there is ample airflow even without the fan engaged. If your car’s overheating then, you definitely have a problem. And I’d recommend immediately pulling over and turning the engine off. I.e., don’t wait (although as you said, blast the heater, turn off the A/C and open the windows in the meantime). I say this because at high speeds radiant cooling isn’t a problem (unless you see that a plastic bag got sucked up against the radiator and is blocking it, in which case, remove the bag and keep the engine running). That means you probably have a circulation problem, e.g., the thermostat froze up or the water pump died. In either case, idling won’t improve circulation and radiant cooling. You will lose the benefits of running the heater, but I don’t think that benefit is enough to override the additional heat generated by the idling engine.

At low, rush-hour speeds, I agree with your recommendations (heater on, A/C off, slightly revving the engine while in neutral, etc.). I’d also open the hood to let heat naturally dissipate more. If the temperature still doesn’t drop, then I’d turn the engine off.

One other thing: After turning off the engine in many modern cars, the cooling system (at least the fan) will continue to run for a while to protect against heat soak. However, you’ll still hear the whirl of the electric motor, so if you’re measuring how long it takes to spin down, just start counting when the whirl stops.