Completing detox subdues the physical effects of narcotic addiction and opioid withdrawal. Psychological and social factors are known by experts as the main drivers of relapse. Stress and anxiety that remind the brain of drug pleasures trigger addiction. Long term maintenance therapy increases chances of beating withdrawal effects by using either methadone or buprenorphine paired with naloxone. Some people stay with this therapy for decades while others recover in months.
Yes, I think a gradual withdrawal of replacement substances would be the best thing. It is so important to find something, some coping mechanism that can help replace the substance in our life. It can just be very important to do and to really guard against relapse.
Addiction is associated with brain, it has nothing to do with the body. Cravings rise inside mind and it sends signals to the body. Mind creates bodily symptoms if a hard core addict does not get drugs. Thus, the first thing you need to tackle while treating is how to control the mind of the addict. Once mind is tamed, body reactions can be controlled.