I only tried the japanese once but there are these things to consider:
1) Lots of small bombs to try and get as many hits as is possible,
2) Larger but fewer bombs so those that do hit do as much damage as is possible.
3) What type of target are you going for and what kind of damage do you want to do:
i) ground targets, destroy or raise the disruption and fatigue levels,
ii) sea targets, do you go for sinking or just damage to send them to the shipyards.
Then there is the production considerations:
1) The cost of a one engine airplane, one engine and one air frame versus
2) The cost of a two engine airplane, two engines and one air frame.
3) The cost of engine and air frame factories to produce said aircraft. Engines can be stockpiled but I don't think that air frames can be stockpiled.
Then there is the aircrew consideration per engines produced:
1) Single engine aircraft units will require twice as many trained aircrews per two engine aircraft units, presuming only a set number of engines are produced,
2) The cost of training the aircrews to the level needed for the most accurate bombing,
3) The number and cost (real and opportunity) of having training squadrons and the availability of the resources to support said training.
Seek peace but keep your gun handy.
I'm not a complete idiot, some parts are missing!
“Illegitemus non carborundum est (“Don’t let the bastards grind you down”).”
― Julia Child