Here's one way to put it all in perspective, I'll use myself as an example. I was a 1.5 PAD smoker...
I would go outside and have a cigarette every hour (sometimes more often). During those 10 minutes or so, I would get about 10-12 puffs off my cigarette (had to take small puffs because my lungs were wrecked).
Now, I pretty much vape constantly - I take a hit, on average, about every 5 minutes. How many hits is that per hour? Yep - 12. The same number of puffs I would take off an analog per hour.
So I'm really *not* vaping any more than I smoked before, I'm just doing it over an extended period because I don't have to worry about it "burning down". I can just hit the pv whenever I want and put it down. The thing to remember too is that when you vape nicotine, it gets delivered to your body *much slower* than when you smoked it. Not just because you smoked a cigarette faster, but because it absorbs into your body at a slower rate when vaporized.
I started off on 24mg juices (and still have one for "emergencies"), but the juice I use all day is now 18mg. I hope to keep decreasing it over time as I go through this process. So in the long run (considering I smoked Lights), I probably am taking in slightly more nicotine than I did before, BUT lets remember that nicotine wasn't the real killer in analogs. The real killers was the tar and 4000+ other chemicals (51 of which were known carcinogens). Nicotine, on it's own, has about the same affect on your body as caffiene does. So I'm gettin' my vape on, and I've actually cut back slightly on my coffee intake, LOL.