As a very very seasoned Dripper i completely agree, when i fill a Carto tank, i will Vape it till its dry, up to 7ml's, then switch to my 4ml tank all in the same day. But with Dripping, i Vape way less than i do using a tank. As Danny said just a few drops and get 6-7 good drags off it, maybe set it down for a while and drip again later. juice lasts me much much longer Dripping, because the Flavor and Vapor is much more intense and like smoking a cancer stick, when its done its done, and I'm good to go... 
