Yeah, 3 to 5 times a day on a regular 808 sounds about right to me. Like a poster above, I'm also using a 3ml carto(Igo), and once a day seems to do ok for the first couple of days of use. After the center tube becomes compromised though, it won't hold nearly that much, and I go back to topping of 2 or 3 times a day. I get about a week to a week and a half(2 weeks here and there, but not very often) out of the Igo carts. But I also rotate some other 808's I get from different vendors on the Igo battery, so that helps relieve some stress from the large carto's.