First of all, how exactly does it progress because they all gain at different rates. I know having a captured unit speeds it up, but are there any other factors, like operating in zones controlled by one of them?

And is there any way to slow it down besides eliminating them? And if there isn't, is there a reliable submod that adds a mission to "slow chosen progress"? I'm beating them in retaliation missions, hunting for their stronghold, but I really look at the avenger defense mission as a playable game over screen. And on the same token, is the avenger defense mission guaranteed once the last bar fills, or do they send an avoidable UFO after you(haven't played in awhile, debating a new start but kind of attached to my current team).