It can also depend on the device you are using. I found that I have been steadily dropping the nic content of my liquid when using an Octopus on my Vamo. Seems to amplify the effect of the nic somehow.
I've been steadily dropping for months now...
When I first started out, I used 24mg in the AM and 18mg for the rest of the day (to help me get over the first cig of the day). Within 2 weeks, I only needed the 18mg. About a month later, I was trying 18mg in the AM and 12mg throughout the day but I was quickly finding that 12mg in the morning (because it was still in my cartomiser) was doing the trick. Since then, I've been gradually weaning it down 1mg at a time and just today I've started vaping 7mg. 8mg was a sticking point for me and I stayed there for quite some time so I've deliberately knocked it down to 7mg because I figure its a psychological thing.
Another poster commented on the nicotine affecting TH. This is one of the reasons why I'm doing it 1mg at a time, so in theory, it'll hardly be noticeable by the time I get down to 1 or 2mg.
I think one of the many, many advantages of using a ecig as an alternative to cigarettes, or even NRTs, is that there is the much greater option to tailor it to your individual needs. Whereas the tobacco companies are keeping us hooked on a drug for their benefit, and NRTs seek to wean us off nicotine at a rate and in a means that just does not work, our PVs allow us to find what works for us. I hope to get off nicotine altogether one day, in part because I'm a girl and if I ever have kids, I'd rather not have nicotine in my system whilst pregnant but that is a long, long way off!x