That, that would require a slightly different macro for each shaman. So if you have 5x shamans, you'd have 5 ATG, which kind defeats the purpose of this setup (one place to store all macros, one macro per class / spec per button ).
Can't have both ... best is:


Step 1:
Shaman 1 big macro
Shaman 2 chain heal or whatever
Shaman 3 chain heal or whatever

do not advance untill chain heal or whatever casting time done (if over the gcd)

Step 2:
Shaman 1 big macro
Shaman 2 big macro
Shaman 3 chain heal or whatever

etc.

Ya more atg is better then goofing with the big macrol.