Several things.
First, I never autosend merchants. Whatever people say about AI unable to handle trade as efficient as human, AI CHEATS. Let say, me, France, early 16th century, my trade level is 10 and I have a monarch with 5 dots in administrative skills. What is the chance to establish 3 merchants in freshly discovered CoT in Zanzibar when sent a bunch of 6? We see three nations sitting there with 5 merchants each, so we HOPE to get at least 4 there. How many got there in 2 monthes? 4? No. 3? No. 1 (ONE) is established, 1 failed and four gone forever without any reasons. We think 'Bad luck' and send 1 year later 6 more. How many get there? One established, one kicked some one and four gone again.. Bad luck? With 10th (level TEN) trade level and Very Good administrator? Doubtless. We start fearing this CoT when next 2 merchants disapear for good in few monthes. But since we are peaceful reach pig with honorable reputation, strong army and navy, rather small amount of colonists, what we do? Right, send merchants to the lone CoT where we have less than 5 merchants. Our diplomats sign two new trade agreements with barbarians in the heart of Black Continent. Finally, we have 5 merchants there! Celebration is clouded: our merchant is kicked out. By whom? Our freshly aquired companions or old trade enemies Oman (with whom we agree to not compete ages ago)? Two years later we still see only 4 nations, including ours, in CoT but rate of competition is higher than even in Venice or Flanders.
Second, AI send merchants 1 by 1 in very overcrowded CoTs. And of course best thing they manage to achieve is kicking someone out. And what? No merchants left to fill in this market whole.
Third: nation with trade agreements with whole world is still very vulnerable to competition. One can send at least one merchant to CoT where somebody you agreed to not compete is keeping monopoly. If you have 4 merchants and nobody is monopolist in the center, you can send at least 2 merchants but often even more. Sending at least two is the best way. But this is
Forth: If you send pair, first merchant has reasonable chance to prepare a place for the second. With lower trade levels three or even four merchants would requier to make the same.
Fifth: some DP choices are to costly to leave for AI to handle them. I mean Free Trade. Bunch of expencive merchants sent to ROTW one by one (and doomed most of the time) can hurt even such monsters as Spain, England, China.
Sixth: (not considered trade as it is but rather domestic policy) number of merchants matter, as well as their cost.Should we kick out some a$$e$ out of our cot? Or send our 36D merchants in 220D CotT in Zanzibariber? If I have less than 12 merchants per year, I wouldn't do that. If we have maxed merchantilizm and 60% trade efficiency, we would get our money back in 8-9 monthes if our first merchant will occupy a sit for long enough time. Most likely we'll need to send two to cover our expences. With free trade maxed, such merchant needs to stand up competittion for long long time.
Seven: This is the end. Got tired to write all these down..
