it is not supposed to increase it.. it is not written in the description.. maybe if it does increase refinrey income, we should tell the developers it is not written in the information of the specialization..

why? still they will be inferior to trade ports.. but if you actually think of social specialization, where trade gets severe penalty, there refineries may actually be useful..

More? If you build refineries on a terran with 700 population, it could give more  income than a terran with full industry, if my instincts are right, though not based on calculations, but would be good to see refineries actually be useful..

Anyway you cannot make refineries be competitive with trade ports.. You would need high numbers for it, and it is not likely to happen.. So what would justify increasing their income rate if still trade would be always better even that way? Or maybe you could give refineries 100-200% bonus, and again Advent would get a disadvantage. Refineries were always strange, and need an overhaul just like Advent resource focus, which is worse than a joke..

not really.. a longer trade chain makes trade much better.. and they will be so much better it will be more a solution to buy metal and crystal from the black market

Something I was experimenting in my last game, is I would social spec my terran/ocean worlds, and stuff them with just enough refinery nodes to saturate all the nearby extracters, plop in one broadcast center on each of them.

Then focus a trade port / industry spec on all my volcanic / ferrus. In the end I didn't spec roids or dwarfs, but still put trade ports on them.

I was playing solo and the income really was quite radical. While its true you can gain more raw results from pure 100% trade, you're also giving that money to enemies if you do it on the black market and they have resources up for sale. Whereas with my setup I didn't even need to buy resources. I was solo and didn't want to setup trade routes either.

Finally I believe its more of a situational thing. I must admit my planet placement luck was amazing, I literally had no overlap in getting the perfect number of refineries with no wasted space. I wonder how often that can happen.

I don't think this is true in current sins implementation. I think that got obliterated in one of the various updates somewhere. No?

Something I have noticed by playing with a friend, is that its much more useful to get tradeports everywhere, than in a chain.

Maybe it's because of my chain that I had, where he got the bonus from, but he was advent, I was TEC, and he got more credits than me. I had a large chain, he had trade ports at every planet...And he got a much higher income...

Of course he did... trade ports  provide their own income. But getting mostly just one long chain is far more efficient, since each unique gravity well on the trade chain adds a small amount of credit income to each trade port along the chain, hence you don't want to just build trade ports everywhere, because it takes a very long time for them to pay back their investment. Plus, you can't really use as much income as that would grant you anyway.