Outside of fights with a huge amount of burst damage on multiple people in rapid succession (Turn 8), double SCH works perfectly fine (and even there it will with coordination and yes, maybe Soil). Double fairies means double "heals I don't have to immediately concern myself with". No need to "spam" Succor.

In some cases (Turn 7, Leviathan EX), I am convinced double SCH is actually better than WHM+SCH or double WHM.