Personally I think that whether or not someone's mental disorder is flaring up, they should stay in therapy. Staying in therapy can help prevent the frequency and severity of flare ups. I'm only speaking for myself here but I already made the mistake twice of letting things get really bad before finally going to a counselor. But at the same time, when my PTSD symptoms were subsided, I would go to the therapy, sit down in the chair, and have no idea what to talk about. So I don't know what's best for other people, but that is just my experience.