the coolant must have enough time to release the heat as it passes through. if you double the speed you cut the time in half. that means it is less efficient and does not remove as much heat .if you could double the air flow across the rad. you would increase its efficiency . either way, it is a fact.
No, either way that is still wrong. Temperature difference between the source and the sink is what drives heat transfer. Not the time.
See, for example:
https://flowkoolerwaterpumps.com/bl...t-need-more-time-in-the-radiator-to-coolBut if that old saw about "time in the radiator" works for you, feel free to keep believing it
Anyhow I agree that the engine is not overheating - but I want it to run at 180-185 on the highway.
