Overdriven pulley how much is too much?

The water too fast is a an old wives tale, proven wrong time & time again.

What is being missed/ignored is this: if you slow the coolant flow through the rad per the wives tale, then by definition, the coolant that is the engine will be in the engine for a longer time, because it is a closed system. The coolant that has now got hotter from being stalled in the engine arrives at the radiator for cooling, & the rad now has more heat to dissipate.