DIY LED lighting placement over aquascape

[mikevangels]

I've been doing a bit of research on LED lighting and so far I've found some great resources here on the forums. One question I did have though was regard to placement.

I've seen that most recommend the L x W / 15 rule or something close for determining the number of LEDs you need for a build. However, my setup consists of two "islands" of live rock for coral with the majority of space in the tank left open for the fish to swim.

Would it be feasible to concentrate more LEDs over the rocks and less over the open space thereby reducing the total number of LEDs needed?

Given their size and the flexibility one has to place LEDs on the heatsinks I thought this might not be a bad idea. Anyone have any thoughts on this?

Thanks in advance and forgive me if this has been asked before.