I'm very new to e-smoking too. Only been vaping for...12 days..
I don't use the USB pass thru too much, but me and my boyfriend purchased one to share, and he spends a lot of his time on the computer. He smokes, erm, vapes, a lot less than i do, and has used a significant amount more liquid in the past week and a half than i have, so i can only assume it does use more liquid.
I've noticed the pass thru gives stronger hits, so that might have something to do with it?