Keep Ironskin up. Healer struggling? Purify? Rolled away at 5% HP? Purify. That’s it. Contrary to popular belief, you don’t need a degree in calculus to stagger properly… lol. It isn’t hard. Prioritize keeping it up. If healer can handle half stagger, let him. If he has full mana and not having an issue with keeping you alive through heavy stagger, let him. If resto druid is spamming you with regrowth and has all his hots on you… yes, you need to purify.
PS. I’m also a Resto Druid, I’m not talking out of my buttocks. If only blizzard allowed profanity lol.
Edit: if Purify means Ironskin will fall, even for half a second, use Ironskin