The 30-day rule definitely does not apply to everyone. Theres been many reports of a person taking a lot longer than 30 days to finally test negative.

Here is one of the more recent ones:
http://boards.cannabis.com/drug-test...a-shocked.html
Burnt Toast Reviewed by Burnt Toast on . Am I a Light or Heavy Smoker? I have a pre-employment drug urine test coming up in a week. I have read a lot online about how to remove thc quickly from your system, and came to the conclusion that only exercise, and dilution on the day of the test works. I read alot about how long it stays in your system, and from what I read, I learned that it's actualy quite rare to stay up to 30 days. It says for OCCASIONAL/LIGHT users it shouldn't stay for more than 3-4 days, and for HEAVY/CHRONIC users 7-10 days (with the exception Rating: 5