Also, the sharp twist in the block causes more of the energy in the impact to be directed into the opponents attacking arm or leg or whatever rather than your own blocking arm. I too, usually just move back as far as my instructor says is need, which his answer is " Just Enough " So I basicly just evade just out the opponents range and follow with a swift counter, when attacked with a jab. Also I like to keep my hands in a position that makes it so that it requires very little movement to block attacks to the head and midsection. and block the kicks with the shins.