Rehab can keep you away from whatever you abuse or are addicted to for a few weeks or even months, and introduce you to various programs, but rehab cannot help build or maintain a life of sobriety and sane behavior.
Neither rehab, nor AA, nor any other program "works." The person has to "work the program," and work it as if their life depended on it. Often, it does.
The questions of whether a program or plan "works" premises a medical patient model, a passive model, as if addiction and abuse were like pneumonia, curable by the best antibiotic. They are not. You do not "go through rehab" any more than you "go through AA."
It can take a lifetime of effort to climb out of the abyss of substance abuse, and a lot of it does not feel very good at all. I have seen plenty of people make the deliberate and conscious choice to live lives of substance abuse. It's a free country. I just resent it when they do it on my nickel.
Schneiderman discusses: Does Rehab Work?