First you must realize the gain is a trade off. You free up the drive to the water pump which drives the mechanical fan but when the fan is running you load up the alternator pulley.
Now the good news, the loaded alt is seldom and only when needed.
With a good radiator and a good automatic controller. The fans should only run when the AC clutch is engaged or when you drive slow/stop and you have no air flow through the grille. Even during that condition it's only running for about a minute.
During warm up, cruising and highway the electric fans are off.
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