I'm not seeing a clear answer - just a few angry stoner replies.
a spliff of good weed should get you stoned in 3 hits. I have yet to see a whole joint smoked in 3 hits, (hence the 1/3 spliff reply). I have however watched people smoke through a whole bag in what seemed like 10 minutes.
It's not rocket science here, they smoked from a bong which may have delivered more smoke but seemed like it used 3x as much. At $40/50 for 4g of quality I don't see the logic in using a bong when spliffs would last much longer - hence the novelty idea.
and yes, I am familiar with vaporizers and they are in no way what I am referring to here.
maybe I should point out that once a spliff is lit, it is not mandatory to smoke the entire thing.