I haven't put in a lot of thru rods, but enough. My take on it is that pattern shouldn't matter.... the steel should be strong enough to easily handle anything the tree can throw at it once the cables are in... once the cables are in the tree can't force the crotch open, but the destructive power to the split (already started in the branch union) comes as the two stems twist side to side, back and forth, in the wind. I have seen one large well-cabled oak split right down to the ground from about 20'. the split didn't open, but it still traveled down the trunk to the crown.
Once we understand that the thru rods are not there to hold the stems together, it's much easier to believe that they will easily stop the twisting motion from tearing down the stem... I honestly don't think placement matters much either. I think that we should just get two rods in wherever we can most easily accomplish that with one of them above the split, but not necessarily above the crotch, and the other at or above the lowest point showing a crack.