hey jonah,
Taking from what everyone has said, chances are you would never need more than three braces per post (one of the three at a different level (if all the braces are the same length)). if you are wanting more than three braces you would have an interior post, and chances are that it is braced somewhere else along that axis as timbeal said.
Yes you don't want mortises all at the same level. Why weaken the post? Change the angle if need be. But for the life of me, I have never gotten any response to the topic, "As your angle changes from 45,45,90 what happens to the resistance of forces"
