Ok cool, but, changing your regular reps to that of a high rep will hit muscles in a different way therefore stressing them differently to how they are used to = muscle growth.Your body will eventually get used to these high reps and then plateau.This does work, but eventually it wont anymore and you will have to do something different to stress the muscle again.
That's the beautiful thing of this sport.
You have to shock the muscle, shock the muscle and then shock the muscle some more!
Your body only knows the intensity of the application you place upon it.