How does this look?

I've never before attempted to use a /cast followed by a /castsequence. Hope it works, because this seems to be the best way for me to get the use I want out of improved counterspell (planning a respec to use arcane blast rotations).

The goal is to have both a roundrobin counterspell for silencing single targets, (yes this is partly for annoying the opposite faction in world pvp) as well as a focus targeted option when focus is set.

Code:
/cast [target=focus] counterspell
/assist main
/castsequence reset=15 counterspell,,
of course the last line will have the commas in alternating order for the other 2 mages.

any problems with this?