Adjusting accessory belts

Just thought I'd share this tidbit. I must have missed this previously. Specifically its about the accessory belt small pulley (not the actual tensioner but #3 in the picture). In the past I have seen various threads question how to adjust this, and some (myself included) have advocated leaving a gap between the belt and the pulley because it just doesn't seem very robust. Well its apparently incorrect. See below:
Image Unavailable, Please Login