Anglo-Canadian doctrine was chosen to counter the germans. The allies emphasis on dug in troops with support from artillery proved to be highly effective as long as the enemy stuck to its doctrine and pressed forward into caculated zones of fire. So my question to you is. What if the enemy, switched their doctrine to "defence in depth" and limited there counter attacks in response to allied advances and used to regain vital ground?? P.S. Dempsey's decision to use the 7th Armoured Division in a deep penetration role while sending the Canadian Amoured Brigade to seize open high ground near Le-Mesnil-Patry resulted in losses comparable to those suffered in attacks by the 12th SS. This was an example of the Allies trying to do the german doctrine.