I've not tested enough to verify everything but I've tested enough to know common market is not the way to go on many things.
I've had every single product needed by my countries contracted through the common market with the exception of Air force Maintenance.
Who came up with the bright idea to have a consumable needed by countries you couldn't obtain everything necessary to produce on your particular world?. At least with glass, selenium is available if your trade strategies are decent and countries don't "NEED IT" directly.
Anyway what I found was there was not enough spending space available to purchase everything and still have enough to buy Air Force Maintenance and I was always running a shortage and had no space to manually enter a purchase.
Additionally this effected my CEO's as the products they were contracting were selling for much less than they would on the open market. So I was buying for more and selling for less, with no improvement in welfare.
So for now, I'm saying "to heck with that" and purchasing only ammunition under contract. It will still effect my CEO as rather than making money those corps are losing money every time THEY need to purchase supplies or I'm going to need a LOT of ammunition corps. You would think with the amount of ammo my meager Army burns through in a month I wouldn't need to upgrade their fighting ability.
It is my "HOPE" the trade off in ammunition upgrades will cancel that out but if not, I will forego the common market entirely. (I actually came to that conclusion years ago but a lot has changed so I figured I'd at least try)
IMHO the meager supply score is greatly outweighed by the damage you do to your countries and corps by buying on the common market.
The only time I've seen corps involved in the common market make even meager gains is when the product offered on the common market is no more than 10% of the standard production.
But, maybe I'm doing it wrong
