That is also consistent with my own experience. Someone I know well (if you know what I mean) was addicted to opium - and kicked the habit. The process of detoxification is very unpleasant - chills, diarrhea, pain in the joints, sleeplessness etc. that go on for about two to three weeks - accompanied by pervasive thoughts that all one needs to do is shoot up and all that unpleasantness will be gone in the matter of seconds. Not to mention the fact that the only people an addict knows is other addicts, since no normal person can bear an addict's company for more than 15 minutes (i.e. when any conversation invariably starts veering to the subject of drugs). And those other addicts bring the subject of drugs while interacting with the recovering addict in every possible way. So the temptation, encouragement and the means of its realization is always there.
When the person I knew decided to kick the habit, he/she realized that the feeling of being deprived of the daily does would make the unpleasantness of detoxification even more unpleasant. For that precise reason, that person decided not to use any professional detox facility, because such facility would invariably monitor that their patients are drug free. Instead, that person acquired a small supply of opium and a large supply of barbiturates. The purpose of the opium supply was to remind that person that the detoxification process is a result of his/her own decision and not the lack of the substance, which was readily available should that person decided to use it. The purpose of barbiturates was to sleep through the more unpleasant moments of the process.
The process of detoxification, accompanied by a radical change in social environment worked, as far as I can tell. I am also pretty sure that if that person was subjected to the normal procedures of the "war on drugs" - mandatory treatment programs, surveillance etc., that person would still be shooting up (provided he/she would be alive), just to defy the authorities inflicting unpleasantness on him/her.
Wojtek