I think I'm a little different on this one. I don't think I could go 8 hours without vaping. Certainly never tried. I remember once a couple weeks ago, I inadvertently left the house without my e-cigs. We were gone a couple hours, and actually, I was fine. Wasn't pulling my hair out or anything. BUT ... If I have it with me ... I use it .... a lot.
In fact, I carry 4 e-cigs at all times ... each loaded with a different flavor. This allows me to vape continuously without worrying about over-heating an atty.
And maybe it is more a "choice" rather than a "need", But I'm a heavy vaper and I am not unhappy with that.