Lustrate needs to be affected by healing debuffs

[Thriar]

It's more like 6. If a smart scholar suspects an incoming healing debuff, they'll store their stacks and keep aetherflow off of cooldown. Taking the MP hit is a lot better than the whole raid wiping because the tank died.

A smart scholar will cleanse the heal debuff first then decide whether or not lustrate is necesary. What you just described(which is how most people play anyway) seems contrary to how you deal with heal debuffs.