The all factory strat has nothing really to do with the issue you describe. You basically describe the problem as one of either "bagging" four or more PQ10+ planets or not.
I'm talking about the broadest possible economic strategies here. I've had moderate success with that gung-ho, oh-this-looks-nice-to-do kind of modus operandi where one only does what seems necessary at any one point in the game; I'm hoping, however, that a wider perspective can pay large dividends. Thus, in the quest for perfect economy, I refer to the all-factories strategy as one of the best steps toward reliable, large-scale economic success I've yet attempted; the bagging-planets issue I include as the greatest apparent limitation.
The act of describing the problem in such a manner pretty much implies and dictates a fairly small galaxy.
I play on Huge galaxies.
I call it the quality over quantity method.
That's my tactic exactly.
Allow me to include that I'm talking the first fifteen turns or so when I say that those PQ10+ planets seem to be essential to huge economic success. Logically the earlier pop growth, social production commencement and morale bonuses of these planets will play a role, and in such a long game as GC2 one might underestimate the importance of one's beginnings.
As for paying others to fight, starting a war for colonies or opting for influence conquering: in my experience, once you realise that you got a raw deal with colonies and you need to start considering these options, you're already so far into the red that it's pretty much over. But perhaps preempting the necessity will render those options less dismal.
Let's all agree that getting high class planets
very early on gives one an unsurpassed boost in many areas. Then, also, that planets in one's proximity depends on chance, and that one has no way of stacking the odds in one's favour.
Thus - and this is the point of the whole thing - what does one do when one doesn't get lucky? Can one focus on industrial, farming and economic research to beef up one's low-class planets, or does one race for Extreme Colonisation to try and get better ones? On the other hand, is an early, expensive and protracted war (fought with Defenders and Soldering 1) the only viable alternative to final economic ruin in such cases?
J.