Depends really on tank. Shadows/sins, due to the problems switch spikiness are better kept filled up. My jugg has enough defensive cooldowns to survive till healer gets their heals of CD
also really depends on the fight. Sometimes trash pack (5 dogs in mandolin raiders when not CCed can hit stronger than boss
And a question about armor debuffs. Do they stack? If jugg, merc and sniper put their debuffs on the target, will the armor go down by total three debuffs or is the strongest rebuff counted only?