Alas that statement makes zero sense from a thermodynamics standpoint. Energy in is vapor out, which equates to consumption (ie. conversion of state). A dead battery will contribute zero energy to the conversion, so there will never be a conversion, so the number of "puffs" approaches infinity. A 5v system will give you 7.5 to 8watts at a minimum, where a 4.2v fully charged battery is going to source somewhere around 6 watts, around 5 watts at nominal charge, and only around 4.5 watts when it's approaching shutoff for low voltage. Putting 4.5 watts of energy into a system is not going to vaporize as efficiently as 8 watts will.
Again - your contention makes no sense from a physics POV.
The frequency of "puffs" will also alter the results for the same reason. A certain number of BTU having already been contributed to the conversion if you puff frequently, therefore yielding more than a 1:1 higher rate of consumption (due to better efficiency of state conversion). The same reason that hot water boils faster. The hot water heater having already contributed energy to the conversion. Which, incidentally, means that vaping in a higher ambient temperature will shorten the life versus vaping in a lower temperature - except that the battery output will be lower, therefore contributing less current for lower heat.
Your consumption rate is anecdotal at best. There is no correlation between your consumption rate and anything else until you show us a high n= with a good r2