I took a health psychology class in college and we talked about marijuana a lot......I think a lot of the class was smoking pot frequently
From what I learned it takes about two weeks for your body to go through withdrawals and get it out of your system. But, it takes a month to two months for your mind to stop wanting it, especially if you are a frequent smoker. Your body actually won't be craving the weed, but you will still think you want to smoke, and will be wanting to mentally feel the same as you do when you are high. Because of this you may actually create worse withdrawal effects in your mind to help you justify "relapse".
But only quit if you want, don't do it because you feel like you should.