maybe ... Katwijk (can) put together a map of how all our fellowships interact
It would be easy enough to note who was offering trades, and what they needed. For a while, in FoE, I was doing an "overall trade balance" report for our family of guilds, and a few of our major trading partners. It was basically just a 4 weeks running average of the posted trades, with the Offers and Needs summarized for each type of goods, and we encouraged the participants to adjust their capacities accordingly.
But, and it seems that there's always a "but" in our conversations, I think that "excess inventory" is not a good thing. If your city has so much excess capacity that you can't even give the stuff away, then you're over producing. Win at All Costs is the bumper sticker, and while it's a perfectly valid playing style it's not my thing.
I prefer the Cost effective Benefits approach. Just in Time with Just Enough is the bumper sticker, and I regard that as a more interesting challenge although minimizing your capacity is certainly every bit as extreme as maximizing your capacity. So excess inventory, and a related means for disposing of those excess goods, is not a problem that I intend to have. Personal preference.
The IMPORTANT concept is that the game is very well designed for folks who are just muddling through, and prefer to pay attention to the aesthetics of the game rather than the grim details of full out manufacturing or cost/benefit ratios. As the game develops I'm expecting to see more and better tools for running a tight ship, but the core of the game is, and should always be, the folks who are happy if they can just stay out of trouble.