Thank you so much!
To answer your question: No, Insight is permanent and acts as a sort of marker for how far gone your Agent is. In general, depending on the operation, Agents should face a lot fewer Insight checks than Stress checks, though.
That said, if you prefer Cthulhu Darks suppression rules there’s no reason you couldn’t tack them on for Insight checks and I do have plans for some more optional rules along these lines in a future supplement.