Not to high-jack but another servo question...control arms.

I have three types in the box: circle with 12 holes; 3-hole arms (6 arms) and 4-hole arms (4 arms). Which ones to use? Does it vary depending on control surface?

Yes, I know to cut off unused ones but not sure which one to start with....I assume the 4 hole if only because the instructions said to connect the control rod the the second last hole which would be silly for 3 holes!