
Just like when a spend one USD dollar it actual ripples through
the economy generating 9 USD of Gross National Product.
So I can see the big use especially in closed loops; and minor where resources maybe be scarce (still makes money if you like a longer term investment with alot of extra capital sitting around).
Even by itself for my one wheat factory. I had an extra fast M4 laying around and used it to ferry real cheap computer components when they hit rock bottom; the local market cells are becoming more expensive using the Econ v3 mod since I have not built another solar power plant yet (price about 20 now), so in a way it is paying for itself off in about 45 hours instead of 75 hours.
That is not bad for a secondary production. It should be on par with NPC at 1/3 rate. So I would expect about three times the wait to pay off the secondary chain compared to the normal 15 hours ROI from the wheat farm. (I have two now).
The bigger chains dealing with ore and silicon and stuff cost more, but pay off ROI much quicker.