joints\blunts waste weed because they are continuesly burning. therefore for every bit of time you arent actually hitting the joint\blunt it is still burning weed.

in terms of the most efficient in my opinion a one hitter waste the least weed but it is also a one hitter making it very unappealing to most people (at least me due to the fact that when i smoke i usually like to smoke a lot and i am with friends).