Heyas Foobar,
I've only been vaping for a couple months now, so I'm definitely no expert, but I know how you feel.
At first, I wasn't vaping enough, because I just didn't think about it if I didn't have a nic craving.
From what I've read, the nic in vapor doesn't get absorbed into the bloodstream through the lungs as efficently as smoke. However, the vapor coats your throat/mouth/sinuses, and gets absorbed through the mucous membrane. So, you don't feel the immediate relief from nic craving like you do with an analog, but you'll continue to get nic into your system for a while after your last vape.
Over the course of a month or so, I went from vaping whenever I thought of it and was someplace I was able to and smoking analogs whenever I got cravings, to less and less analogs and more vaping, to no analogs at all about 10 days ago. I cut down on analogs not so much because I wanted to quit smoking, as much as they just tasted more and more GODS awful!
The day after I smoked my last analog, I got my first vv mod, and just went vape crazy! I was lightheaded all day every day, and got frequent headaches. I've since had to lower the nic content of my juice from the ~25mg I use to use, to ~8mg now, which seems to let me vape all I wish without ill effects.
So to answer your question, I don't know
I'd say its different for everyone. Vape as often as you wish to, as long as you're not feeling any ill effects from being overnic'd, and as much as you need to in order to avoid those nasty analogs. Experiment with different strength juices, if you want to vape more or less than you are now. If you have a favorite flavor or three, you can order one high strength and one 0mg, and mix it to whatever strength you want.
Hope this helps
Maximillian the Recently Overnic'd