I just watched a class-25 (Serene, not even extreme!) planet being developed by an AI. I'm no min/maxer, but I could do better than this by far.
The first thing it made was a Ship Yard. 30 turns later...
The planet had a manufacturing tile - the AI placed a factory there. So far so good. Then it put a factory on the other side of the planet, adjacent to the colony capital. First mistake - you'd get two tile bonuses overall by putting the second factory next to the first, not just the one from the colony capital. Inefficient, but not all too bad.
Then the real problem started. So far the AI has placed down two factories, right? It then waits for them to upgrade into the highest tier it has - at the time, Mega Factory. Lets look at stats:
A Basic Factory has +25% manu, costs 30, and requires 0.25 maint
A Mega Factory has +40% manu, costs 67, and requires 0.75 maint
A +15% increase, for 112 cost and 0.5 maint
It could have had 3 more Basic Factories, with adjacency bonuses, for +75% manu, 90 cost, and 0.75 maint. (Even though maint is higher, it could also have just made two Basic Factories, for +50% manu, 60 costs and 0.5 maint). Add adjacency bonuses in, and you could be at +60% extra manu.
Seems like a no-brainer. +15% increase is so much better than +135%, right?
Add to that, that each Basic Factory can be completed sooner, making the building of the next structure or update quicker too.
When the first Mega Factory completed, it started work on a third, next to the second and the colony capital. Slightly better.
Then, unfortunately, the AI went mega bankrupt. It took around 50 turns (and that's not an exaggeration) for them to get planets back to normal.
Then another AI (well, my faction on soak) destroyed its shipyard. 11 turns later... It started building a Research building on a research tile. Good thing it has so much infrastructure down, on this class 25 planet.
In 91 turns, plus 314 manufacturing (two Mega factories, and one Basic) - so another, say, 30 turns, the AI had managed to build two Mega Factories and one Basic Factory (and two Ship Yards). 120 turns for a barely functional planet.
My observations:
The AI only seems to queue two things at once. Auto-upgrade means those two things are (if they're the same) going to get fully upgraded before other buildings are made. They seem to value Quality over Quantity, despite being horribly inefficient.
The AI rushes far too much. With the Beta 6 increase in ShipYard cost, the AI building a ShipYard at every planet, and the AI knowing where everything is (ie, they constantly rush colony ships and constructors), they're bankrupt, or close to it, within turns.
Ok, this was on Beginner diffuculty. I can't imagine it being much more efficient on higher difficulties, but I'd have to watch them develop a planet to be sure.
