Honestly, I don't know the rule. I was just looking at my cams and if the string were to get longer(stretch) the cam would rotate in a fashion that would move the string away from the bow (increase BH) and the ATA would increase. So, in my mind, I would shorten the string to get the proper ATA and then check the BH and DW. If it didn't work then you can always put it back to the way it was and try adjusting the cables.