Why is three meetings a day for thirty days a good idea? Or one every day for 90 days. Or any regular committment.
What you're basically dealing with are deeply ingrained responses to wanting.
Wanting something that is not, to be.
Wanting something that is, to not be.
The result being drinking. In other words 'bad habit'.
By setting youself up to go to a lot of meetings in a space of time, and sticking to it no matter what, you start to rewrite your habits. In time your habitual response to wanting becomes 'positively dealing with the wanting'.
So, the key is to persist. Make the commitment and stick to it, no matter what!. The change happens when you have had enough and talk yourself into reneging - but: you don't. You stick to it no matter what. That's when the habit changes.