Last game I played, with 16.27 from start to finish, the biters were set to expand, I double checked with console commands, and not once did they do so. If I cleared out an area, it stayed cleared out. If I pushed my defense line out to expand over a continent, the scores in those chunks never triggered an attack, and the bases were too far away, and they never filled in the space between, so 90% of my defenses never got attacked, the only ones that did I put right on a small land bridge between masses, and used it to farm biters for Alien Loot Economy.

do you have a save I can look at?

I figured you'd ask. I think this link should work. https://drive.google.com/open?id=1-mBu9PfcCbtJoKayb2EvNmpeolO10XLs

Because your map consists for lots of water with very narrow paths, I would recommend you re-enable the vanilla ai in the mod settings along with Rampant.

This is due to the limited amount of processing I can do in lua and not cripple performance. I resolve paths at the chunk level, so if you have a really complex natural landscape that will cause rampant some issues.

Ahhhh. That's disappointing. But even the south deserts never expanded, but I guess once the AI gummed up, it could never clear it out. Thanks mate.