I read it somewhere, but I forgot... And how many markets give the minimum and final exchange rate? I think it's 9, right?
So, if you have markets in 4 castles and enter the outer market, do you get the maximum benefit from the exchange?
No, that's not how it works. Castle markets don't stack with the outer market. With 4 markets in castles and an outer market, the exchange rate will be the same – in the castle, it's like having 4 markets, and in the outer market, it's like having 5. For the best exchange rate, you need 9 markets in the castles.