I know this is probably obsolete, but in the 70's Consumer Reports came out with an article where they (probably other researchers, this didn't seem like standard CR fare) forced three "standard" joints per day on each of several monkeys and an significant alteration of their mental activity was measured. I saw a photo of one of the monkeys and looked up the breed. On average, their lung capacity was 1/15 a mature human's lung capacity. So by human standards, each monkey was being forced to inhale 45 whole (not shared with others) joints daily! In that light, it seemed like a rather desperate/pathetic attempt to force a negative result!
I stopped smoking pot when they announced they would start drug testing at the nuclear plant I was working at. They gave a 6 week warning and included information on how long each drug took to clear the body (4 weeks for pot, IIRC). I liked my job, so quit smoking.
Interestingly, it impacted the Document Control Department (in a nuclear plant, there are procedures to ensure that there are no obsolete documents in circulation),they lost the people who were friendly about going to pull a print for us engineers and it became a royal pain to get help. One day a friend of mine started flicking the light switch on-off (it was by the entrance to the room) and yelling "help!" in a Mr. Bill voice while the staff just sat at their desks and studiously ignored us!
I'm not sure this story to make a case for or against pot, it was just a surreal experience.
What a world we live in!
Of course, the drug testing program was a new "game" and there were a few A'holes who were reported (anonymously) for doing drugs on an almost daily basis just to harass them (there were 20,000 people working there when construction was full bore). The rules were adjusted so no one would be tested more than a maximum of twice a month.