I'm not totally sure I understand the question. The ones on the top side have a more aesthetic focus. I put the larger ones on the bottom to add a additional structural reinforcement - both sides, etc. Because of the branch split the slab needs a lot of structural reinforcement.

I guess I just like the way "butterflies" look in general. It sounded like you were only putting these on the bottom.

No no. They're on both sides. Shows the top side at the bottom of the thread. They fulfill a key structural purpose too though. So here I wanted to reinforce top and bottom.