Yeah you guys are all correct on how reverse tolerance works, for most drugs that is. Not so much with the herb. Reverse tolerance with the herb works something like this. The more you smoke, the more you body gets used to your cannabinoids being activated, the less stoned you feel. However, those who smoke more often don't need to take as long of a break to lower their tolerance. For example, I have a buddy who smokes cannabis medically all day long. 10 rips off of the bong will give him an average buzz lasting maybe an hour. If he were to take three days off it would feel like his first time. If he took a month off he says it's as gnarly as shrooms because his body is so used to it.
Now for those who smoke maybe once a day. A week will do you good. Those who only toke on the weekends or only a few times a week will have to take off a month or so to notice any drop in tolerance.