interesting... i've been thinking about this with a white pine timber that is presently hewed to 16*20, that I was considering whether to chainsaw mill it in half and half again, or take (less useful) planks off the sides.
my general sense is to hew to the heartwood and then use the timber as it is and see how it would fit into a structure, but in this case it's too big to lift/drag from where it fell. the tree has been down for 3 years now and this timber has been without bark and squared for 2. i wonder how it would move if sawn down the center.