Strategic bombing was utterly worthless before 1943 except as a propaganda exercise and advancing up the learning curve. There should have been a token British bomber force for the sole purpose of occassionally night bombing Berlin and other cities as a propaganda exercise and learning curve lessons, and all other bombers given over to maritime patrol. Simply put, the people at Bomber Command were wrong.
By 1943 however, good enough designs and plentiful numbers (plus having severely reduced the U-Boat threat) makes strategic bombing somewhat viable for the US and Britain. Then with hindsight of what works and what didn't, you can design a bombing campaign that will be more effective than IOTL at less cost. You are still going to get hammered in 1943 before the introduction of long range escorts, but it's probably not politically feasible to wait until they are available.