Is there a general rule on how many times you should plunder

[Sirerik]

I agree that people on the plunder board are fair game but I check their description to see if they have any rules of engagement or threats. For example Black Sparrow says
"Rules of Engagement:
-Voodoo usage is an act of war
-1 attack for 1 counter
BEWARE!
1 attack = fine
2 attacks = YOUR DOOM!"

[Bmw]

most people will tolerate three attacks before they will start attacking you back with me if you attack me once and if my fleet is around there i might attack back i might not and if you attack me three times usually i will move my fleet to there and start hitting you as much as i can so long as its in a count of three's