I will share my own experience as a long-term recovering alcoholic, and that was I completed in-patient rehab, and thank God.
It was exactly what I needed. I was taken out of the environment where I was doing my drinking/drugging, and started very intensive work on healing. There was a lot of one-on-one time with my counselor, which was another Godsend for me. We were required to work through the first 7 steps, and I am also grateful for that. Left to my own devices, I know that outpatient would not have worked for me.
Sending you hugs of support!