I don't know. But I'm going to guess that it won't add anything to a
sound, pressure treated post and it might actually weaken an untreated
cedar one. And given the gentle use it's going to get from you anyway,
it's probably not worth the extra work.

J.

Larry Blanchard wrote:

My original question remains unanswered. Would a bolt/screw/lagbolt through
the post just above the notch resist such splitting? I think it would, but
wondered if others agreed.