I started my last Sweden campaign to test how many protectorates I can collect in the course 200 turns. Initially, I tried to be nice and not to get too many expansion penalty points. In mid game I decided not to care since I didn’t feed it was fair when I don’t get my penalty reduce for giving land away.
This is what I have collected in by the end of the campaign:
It is hard to count but I think I got 30... This is how much trade $ they are generating:
And this is my area of control:
I don't have enough time to finish off the Americas...
Based on my experience, I noticed that there are two factions are not suitable to be a protectorate: Courland and Martha due to their aggressivness
Also, AI like trading territories so it was hard to make sure only Indian fractions control the Indian Continent etc.