I’ve never used nicotine, but the problem I would expect someone trying to take in more nicotine per dose to cut down on the number of doses is possibly puffing on it more often out of habit, boredom, failure to keep track, etc. and taking in a lot more nicotine overall, or just getting used to the higher levels and then intentionally taking more.
...but as most previous posters said, there’s not a lot of tobacco/nicotine talk around here.
There is
a thread about vaporizing tobacco though, if you want to consider using the leaves instead of an extract. I don’t know if there’s definitive evidence yet, but my guess is that’s safer than a lot of the liquids.