It's not TOO bad. I feel SCH has issues but Excogitation is not one of them.

Use it when Susano EX is casting Storm Splitter, cast Adlo, and you nullify the tank buster entirely allowing you and your co-haler to do some dps in the meantime. Storm Splitter can be nasty especially as Susano melees right afterwards, so the tank needs to be healed inbetween the two - and Excogitation does that automatically.