[thejeff]

What I meant by main research goals is not that there is some path that is better for all nations, but that since these tactics seem to be geared towards the nature of your enemy, rather than your own strengths. That makes them seem more opportunistic to me, since you don't know when you start researching who that's going to be. Build on your strengths, when you know who you're going to fight and what he's likely to field figure out what you've already got or can get quickly that'll work against it.
As you said "depending on circumstances."

I'm certainly not saying they aren't good tactics and I'm probably guilty of overlooking them most of the time.

Deep ones and Numbness might be a good counter to blessed Knights of the Deep, but they don't fare so well against R'lyeh's mindblasters and chaff. Nor against archers if you're trying to move onto the land.