Actually rolling economy first is not always good.
-As Germany, Innovation is more important for getting Late Fighter-Industry.
-As Austria, you can rush to Russia or Italy with researching offense first,
-As Turkey there are huge benefits getting bunker tech or late fighter immiadetaly.
-As UK naval techs can cause serious troubles for Germany to keep its navy.
Also I agree that there are only 2 really weak techs which are mobile warfare and merchant marine.
I agree with all of the above, except the part about mobile warfare being weak. I've seen that tech used to devastating effect. Granted, that was in games which had a gass limit. Now that redrum wants us to play without house rules, you could argue that the effect of that giant cavalry stack (movement 3) could be replicated with a giant stack of gass instead.
But . . . there are still some circumstances where cavalry would be significantly better than gass. To give one example: suppose Russia has deployed a massive conscript stack. Sure, you could gass the stack. But, each gass costs 3.5 - 4, and kills slightly less than one conscript (cost of 2). Better to use creeping barrage + mobile warfare against a force like that. Mobile warfare allows cavalry units placed in Vienna the opportunity to attack Belarus the very next turn.