You're not factoring in the fairy's healing capability at all, which is a free ~55 pot/s that you don't even have to think about while dodging stuff, or more with the 40% pot boost from rouse.

WHM can CureII + tetra once a minute, SCH can Adlo + lustrate three times every 45s. Or adlo+lustrate+lustrate. The potency for both methods over 45s is the same if SCH alternates between adlo+physick, and more than WHM if SCH spams adlo (but not sustainable due to mana).