Let me start with many thanks to Yeol for a wonderful job! I was a bit bored after playing TF2 for like a week but this mod made all the difference. Kudos!

I was so impressed with the mod that I started working on a map of Europe. However, when calculating the numbers of factories required to sustain the whole continent, I've noticed a problem.

First, some background. I have 55 cities, they have in total ~2000 needs of IND and COM (and MAIL). Knowing that they will grow up and wanting to add some variety, I've decided to have 4800 maxed-out production of both IND and COM on the map.

In 1850 that's 4x COM center (lvl 4) + 6x IND center (lvl 4). The supply chain to sustain that is the following (I truly hope that I haven't made any calculation errors here or later on):

* 4x Food Processing (maxed out lvl, like all the others)
* 4x Textile Mill
* 8x Livestock Farm
* 8x Crop Farm
* 2x Cotton Emporium
* 1x Slaughterhouse (!)
that's for COM [27 buildings + 4 COM centers]

+

* 3x Tools Factory (lvl 4)
* 3x ConMat Factory (lvl 4)
* 3x Steel Mill (lvl 2)
* 6x Iron Mine
* 6x Coal Mine
* 3x Brick works (lvl 4)
* 3x Clay Pit
* 3x Quarry
* 6x Sawmill (lvl 2)
* 12x Forest (!!)
for IND [48 buildings + 6 IND centers]

OK, that looks pretty good (with some small issues that I will list below). Now, when we change the era to 1900, we need 4 IND centers instead of 6 to get the same 4800 production when maxed out, that also looks good. But the numbers of the buildings in the rest of the supply chain start to look a bit weird.


Comparing the same 6 IND centers as in 1850, we now need:
* 6x Tools Factory
* 6x Fuel Refinery
* 2x Modern ConMat Factory
* 4x Concrete Factory
* 4x Limestone Quarry
* 4x Window Glass Factory
* 4x Sand Pit
* 8x Steel Mill
* 16x Coal Mine
* 16x Iron Mine
* 12x Oil Refinery (!!!)
* 24x Oil Wells (!!!)
that's 106 buildings, twice as much as in 1850! Granted, it produces +50% more resources (7200 not 4800) with this higher number of buildings but you can see where I'm going with this...

Let's look at COM in 1950. First of all, in order to get the same 4800 production, now we need 6 COM centers rather than just 4. The supply chain for those 6 COM centers looks as follows:
* 6x Appliance Factory
* 6x Electronic Dev. Factory
* 6x Copper Mill
* 6x Steel Mill
* 12x Oil Refinery (!!!)
* 12x Copper Ore Mine
* 12x Coal Mine
* 12x Iron Mine
* 12x Chemical Plant
* 24x Oil Wells (!!!)
That's 108 buildings from 27 buildings in 1850! That's almost 5x increase! Not to mention that in order to sustain both IND and COM supply chains, in 1950 we need on such a map:
* 28x Iron Mine
* 28x Coal Mine
* 14x Steel Mill
* 24x Oil Refinery
* 48x Oil Wells (!!!)
so they would not compete against each other. All together that's 214 buildings (including COM/IND centers), in my case more than 4 buildings per city on average. Way too overcrowded, especially compared with total of 85 buildings required in 1850.

tl;dr

To summarize this, here are the issues I've identified:
1. COM supply chain in 1850 requires too few buildings, only a bit more than half of the buildings needed for IND chain
2. Slaughterhouses - only 1 maxed-out SH is needed to sustain the whole 4800 COM chain.
3. Forests are a bit of a bottleneck in the 1850 IND chain.
4. 1900 IND and 1950 COM chains require ~2x too many buildings.
5. Oil Wells + Refineries are a HUGE bottleneck - Steel needs 70 buildings in total to get the final product, Refined Oil needs 72 to get only a resource needed for the next step (->Plastic or ->Fuel). Also, Refined Oil is used up for Plastic and Fuel separately - unlike Fodder/Cows in 1850 which produce the resources for both COM and IND simultaneously (in Livestock Farms & Slaughterhouses) reducing the number of buildings required in both chains.

still tl;dr ;)

So finally, here are my change suggestions:
1. Slaughterhouse: output x0.5 per level (max 600 production)
2. Forest: 1lvl -> 2lvl (max 400 production)
3. Oil Wells: 1lvl -> 2lvl (max 400 production)
4. Oil Refinery: 2lvl -> 4lvl (max 800 production)
5. Modern COM center: output x2 per level (max 1600 production)

That would produce way more balanced supply chains, in my opinion.