Typically 3-6 mg is what most people that vape using powerful sub ohm mods use. They go through several 4 ml tanks a day easily like this.

People using smaller ego style devices generally use 12-18 mg strengths.

Each cigarette contains anywhere from 8 mg of nicotine up to 20 mg of nicotine.
A pack of cigarettes would contain 160-400 mg of nicotine.
Smoking a pack of cigarettes would be approximately 20 mg of nicotine absorbed.

Your 10 ml of eliquid over 2 days at 6mg = 30 mg a day used (not all absorbed)
The studies I have seen point to needing 50 mg strength eliquid to even approach the same amounts of absorption in the blood as a cigarette over an equal smoking time frame (5 mins).
The study I have posted below shows people using 18 mg eliquid needing to vape for 35 minutes to reach the same amount of nicotine obtained from a single analog in 5 minutes. So using 18mg liquid, and smoking for 11 hours would land the average vaper about the same nicotine absorption as a pack of cigarettes.

Nicotine absorption from electronic cigarette use: comparison between first and new-generation devices : Scientific Reports
http://www.nature.com/articles/srep04133

In the end, I would not be overly concerned about how much nicotine you are using, rather count how many analogs you are not, and the 4000+ chemicals contained in them.

Just find a nicotine level that allows you to stop needing to vape non stop, once you get comfortable doing that, Then you can try slowly tapering off the amount of nicotine you use and reach 0 if you wish.

You may also want to have 2 strengths, a higher level for busy time so you can get you nicotine fix in easier/faster, and a low level to sit and puff on.

This I got from https://www.e-cigarette-forum.com/fo...o-much.720410/