I know two German factories sounds scary (I told you it takes guts to build them...), but here's my reasoning.
Since France is usually finished off by turn four (Summer '40), I can't see how starting a factory on turn two could possibly consistently impact the French outcome. A turn two factory loses at most 12 points of production that the Germans might have gotten into France instead of into the factory. If the battle is so close that 12 points would make a consistent difference, then the Battle of France would have to pretty much be a 50-50 chance matter to start with (and which we know it is not, now that French colonial forces stay away to keep the natives under control).
As for Barbarossa and German factories encouraging Russian stalwartness at the borders, if you do the math, a turn two factory has almost broken even at the start of Barbarossa (meaning it's almost a push as far as the number of forces the Russians see as of Barbarossa). A second factory started on turn three puts the Germans down something like 20-25 PP as of the start of Barbarossa (if my math is right), and which I cannot see being the difference between the Russians being able to hold at the border or not. Since the Russians (probably) have to fall back from the initial on-slaught against only a (slightly) weakened German attack, the extra few turns brings the second factory pretty much to the break-even point also (and which occurs the Winter '41-42 turn).
And, as they taught me in B-school, once you hit break-even, the rest is all gravy.
dd