When I switched from bongs and bubblers to the Volcano I probably saved about 25% right out of the gate. Then later on when I realized you need less in the chamber than it looks like I saved a bit more. I was at about 1.5oz/month back when I was combusting, now after 10 years of almost exclusively vaping I consume about 1oz/month.

I generally try to grind an amount that I will use within a day or so. I live in a low humidity state so if I grind up too much and let it sit around too long it can dry out more than I would prefer.

Reminds me of this