Research shows that there is a 50 to 80 percent reduction in OCD symptoms over the course of 12 to 20 sessions of CBT and ERP treatment.
That number of sessions may even be lessened if the treatment is performed in an intensive program, such as a partial hospitalization program or an intensive outpatient program (PHP or IOP).
The best predictor for the success of the therapy is the patient’s willingness to do the homework that is assigned by the therapist. Therapists are not responsible for their patients’ improvement. Therapists are more like a coach than anything, they have the “plays,” but the players need to execute the plays in order for the team to function.
Similarly, the therapist can design a treatment plan and the exercises to do, but the patient has to do them in order to see improvement.
Just like only playing a trombone at your music lessons will not increase your trombone playing ability very well, only doing exposures at the therapy session will also not be very helpful in fighting your OCD.