My earthquake macro is similar.

But as well as turning on next click in the first step. I createa a 2nd step which does this:

Send > Elemental Shamans > Mouse 1
Mouse Broadcasting off > All

I then change the hotkey settings so that steps are done on push or release.

So when I hold the button, it forces all my cameras to be thesame (view5) and has the earhquake targetting reticle on the ele shamans. When I let the key go they all cast earthquake.

I dont really need to see the reticle on my tank because the cameras are all so similar.

I occasionally get problems where the tank or helaer mouse is a bit fucked after I use my macro a few times and mouse broadcasting breaks from the main screen. Still trying to work out why it does that every now and then. In my send next click I'm using KVM mode so maybe thats why.