For 5v5, 2 players, 1 Healadin and 4 Eleshamans, when if ever would it be the optimal strategy for the shamans to stop DPSing and go into what I would call "self preservation heal spammin', totem droppin'" mode?

I play the holy pally so when I get CC'd, I'm acutely aware of my sudden inability to throw some large heals on one of the shamans. I have to make a judgment call at that point whether to bubble or use the trinket. Using the trinket, I don't mind so much, if I need to, but if there's a priest nearby, and I'm CC'd (but not cycloned), then using the bubble would probably be a waste of time.

So that brings me to the question -- when should I ask my shaman partner to switch modes until I recover from my CC, or should we accept the *potential* loss of one of the shamans as an acceptable risk in return for continued focused fire?