Where to place on rocks?

[Dan7575]

My live rock is old sps coral with all the stubby arms coming off it and I struggle to understand where to place corals on it. In particular the spreading type corals like a Favia, I worry that If I put a frag onto the rock it won’t have anything to grow onto once it comes to one of the gaps between the arms, what will happen then?

 

[reef lover]

Most likely will shelf out until it hits another rock.