383 build for efficiency

I don't understand how setting your cruise rpm at peak torque gives you maximum mileage. Sure that's the highest VE % but in a street engine that's usually around 3500 rpm. A engine turning half that rpm at cruise can't be burning more than an engine spinning twice the rpm (peak torque) and on top of that the engine spinning lower has less % VE so its ingesting less air and fuel even though it's way less efficient.