Look at the time wasted bombing the ball bearing plants. Then they bombed the fighter factories. For some reason the allied planners figured that Hitlers war machine ran on ball bearings and forgot that if you bomb the refineries and storage tanks the entire effort collapses. If they had gone only after the oil supplies in early 1943 when the US started sending large groups of day bombers the whole thing would have been over by late 1944. All of the fighters would have been grounded and the U boat fleet would have been stuck in port. And no panzers to attack the army when they invaded France.