I dont measure out anything but it is a common question I am asked. I wish their was a diagram or formula that did that but alas we all react to the sacred plant differently.
When I talk to a person about vaporizers, generally they are very ill, I talk about mapping what temperature and amount helped them best. They keep a sort of journal and then they can compare later and get an overhead view of how it affected them and they can use that as a tool when determining what is optimal for them.
Recreational users basically do the same thing just dont write it down as much, they tend to play with a few temperature/volume of material variances, low, medium, high and then pick a general temp setting/volume of material and basically fine tune from their. Sometime adjusting the temperature to match differences in moistness in material and ambient temperature from time to time.
I dont think many people actually weigh out the amounts they use. I would be interested to see how your tolerance reacts as you would be seeing your tolerance in far more detail than most people. I think that is very cool and almost worth the trouble to do it in my view. To me I dont weigh mine out because I vape for health issues and recreation so my use varies and not solely based upon just need. I also do not have a scale that weighs such small amounts.
Vaping is great in that you can dial in to precisely where you want to be if you take the effort to map it out like you do. It truly becomes a tailored medicine but I like to be able just float off and the feeling of the same would soon begin to bother to me. I like the variety and variances of a larger degree scope but I salute you. Their is much knowledge to be learned by doing that.
I hope that you speak on your tolerance levels later on and how you account for it. Question, do you normally use the same strain or do you get a variety of strains? I find variety works best for keeping tolerance in check but I never looked at through the scope in which you can.