For all the "solo heal" encounters it's mostly DD that should not get hit. It's perfectly doable. Like Garuda for example. DD never gets hit in theory. Titan EX: stomps and maybe upheavel would be a bit of a pain for SCH. Other than that, there should be no dmg on DD..

So basically high exp groups can have some fun and do the 1 healer, 1 extra dps trick.