The PD and other vapes with small bowls are efficient in two main respects. One is that the narrow bowl provides hits you can easily handle/process. The other is that bag fillers like the 'cano, and other vapes with large bowls, allowing big hits, will encourage you to load large and take those big hits, part of which will be wasted in a premature, big cloud of exhaled vapor. You proved you can overcome the tendency to use a lot, in loading that small amount in the 'cano. But those loading such a small amount will be few and far between. The biggest part of vape efficiency, assuming quality models are used, is psychological, as far as how the vape is loaded and hit. I used the most herb, by far, during my bag fill days, while using a log vape with just a stem (no waterpipe assist) always does the best job of conserving my supply. Granted, I'll get higher with just a few Cloud hits, vs. an evening of vaping with my CRZ. A big hitter and a log vape- always a good combo to have.