The added drag of the alternator would be a fraction of what it takes to drive the clutch fan. Also, as you stated, timing is the whole point. In the summer, every time you stop the clutch fan engages causing lost power (and lots of noise) when you need power the most-for acceleration. Not that every takeoff should be at full throttle, but any added drag while pulling away from a redlight or stop sign will affect the way you drive. Most of us try to compensate for the lost power by increasing throttle resulting in poor fuel efficiency in addition to the lost power that is already being experienced. The clutch fan even creates drag when it is not engaged. If you don't believe me, try this: start your engine, open the hood, now try to stop the fan. If you use your bare hand, you'll probably lose a finger. If you use some other object, The fan will probably shatter on impact. The drag that drives the fan, even when it is disengaged, affects your engine all the time as long as your engine runs. It's much less than the drag created when the clutch is engaged, but it's still there.