CBT was crap for me. I did it for at least 4 years. The therapists were like, "CBT fixes everything!" They were huge fans. My mental illness was too severe for CBT to do anything, but they were so determined that CBT was the answer that I suffered needlessly.

DBT was super, super helpful.

In my opinion, CBT is good for mild to moderate severity. Beyond that, a person is truly unable to think or feel differently. They can't just think differently to feel better. DBT deals with those INTENSE emotions. I got on a slightly better med and started taking DBT - changed my life.