The issue of strength in the hands or forearms is not that simple. Strong hands allow you to have the club more in the fingers rather than the flat of your hand but strong wrists/forearms allows less clubhead twist or wristbreak in the rough. So it's a good thing?

Well too a point!

Too much muscle in the wrists can have an adverse affect.

Swing speed and good rotation is reliant on flexibility even in the wrists - some say problems start in the hands (often too tight!). Try this - clench your fist as tight as you can and now see how difficult it is to rotate your hand about your wrist. Now relax the hands and try the same - it should feel more flexible but importantly you now have a greater range of motion.

Also remeber that the lower arms and wrists contain extensors and flexsors therefore any exercise needs to be symmetrical. The motorbike reving should also be done forwards and backwards, and with the palms face up.

Hope this helps.