Originally Posted by
Magic-Mal
It is relevant because very often you have no stacks and no aetherflow ready. Especially if you just blew stacks on AoE. So at that point you're just using Ruin with Bio III + Miasma III. Remember you only get 3 stacks and Fester/Painflare/Energy Drain is only a 5sec cooldown. So there's a 45sec gap.
But the actual point of the comment was to point out how SCH has a spammable Broil III at like 250 potency and SMN only has Ruin, 100 potency and a 15% chance to use Ruin IV which is only 200 potency...