Addiction - How long until you started breaking "the rules"?

[kant]

It's commonplace of those wishing to reap the benefits of opium while staying on the safe side to set up a bunch of rules devised so as to evade falling into a habit. The rules are always backed up by the assumption that knowing enough about the pains of opium and the mistakes of others will be sufficient to keep the user in line.

But the history of opiate use has seen this assumption fail so often that one really has to doubt whether it can be made at all - whether all the information, experiences and wisdom is actually enough to be able to stick to self-made rules one believes only his will and reason will help to maintain. Just remember any time you ever made rules for yourself - I believe most people will be familiar with the feeling already present before even formulating any rules that you cannot really convince yourself that you are actually going to follow them. And then, while having these doubts, the overpowering desire for the opium pleasure sneaks into the line of reasoning and you end up with a patchy doctrine.

Anyway, that's a bit of theory behind failing. But how successful have you, long-term users, been in practice? How long have you managed to avoid addiction or to maintain steady use after kicking a habit, by actually following the initial rules?