The system uses both convective heat transfer and conductive.
I personally agree that if fluid is running through the system at an alarmingly fast rate and only in contact with the heat source for a very short time, it won't absorb (or dissipate) the heat. However, that would need to be a very fast flow considering the areas of heat source and exchange in an auto engine. The radiator and the inherent restrictions within the cooling system (block design/radiators/heater cores/hose sizes/etc) will slow the water down enough to work effectively.
In most cases it is the lack of water flow that causes over heating! Do what you can to speed water flow (a larger and more open radiator/bigger water pump/removal of shape edges and casting burrs/ increase hose sizes where possible and remove any kinks/etc) and engine cooling will improve.
You don't fight a bush fire with slow moving water
Certainly in my case I'm not looking for maximum (expensive) efficiency, but rather economically effective.
Many years ago on my old track car (which was also an Italian daily) would over heat very quickly in stop start traffic if the outside air temperature was above about 27C. I removed the thermostat completely (and yes it was operating correctly when I tested it). This completely solved the over heating problem.
It also had a subjectively measured side product. The engine idled better and I suspect it revved out a little quicker. This is quite possibly due to the reduced load on the engine due to the reduction of back pressure on the water pump. Before we start flaming me, this was a subjective perception and not proven scientifically or statistically.
Again my opinion, if you are running high octane fuel and/or higher compression and don't do very short trips on very cold mornings, remove the thermostat completely and allow your engine to warm before pushing it - life will be good.