Not easy to answer. There are a lot of variables we have to take into account for the extraction rate. My guess would be that the number of draws might not be among the most important variables. Which vape? What is in the vape? How is the particle size of the grinded material? How high is the temperature (along the material)? What kind of heating and air flow? How big/long/strong is the draw? Those are questions I would ask first if I would look at it scientifically. Either in order to keep those variables constant or to ask the underlying question: how to get the most out of my weed?
Back to the question of how many hits for a full extraction. I think a full, i.e. complete extraction of all the desired active substances, is not really possible. I don't know of any scientific paper about it, but some people checked cannabinoid contents before and after and the results suggest that you can be very happy if you accomplish even 50% extraction rate.
It makes totally sense that more hits lead to higher extraction rates. I think, you want to know whether its worth the effort to keep going, right? We know simply from experience that the first hits have "more calories", that means they have a higher amount of cannabinoids per volume of air. After the bulk of cannabinoids is extracted in the first 3 or so hits the ratio of active substances to air will become increasingly lower after every subsequent hit while harming substance (Benzol ect.; depending on temperature) and bad tastes could be getting more and more into the mix.
It would be a totally interesting question to find out the sweet spot of maximum extraction/effect and minimum harm!
For now it probably comes down to personal preferences or tolerance to avb taste how long someone is doing it. Most times I like to do temp-stepping in order to get a long session and the most out of my weed. Sometimes I stretch 0.03 g for 10 draws with my Vapman. But I don't want to vape every weed "until the end". There are strains that have some nice tastes left even when considerably vaped and others that suck right after the start. I remember a strain called Berry Haze which had a crazy long lasting taste. I even tried successfully to vape it first in the Lotus (which is a convection vape) and after that, because it had only a light brown color, grinded it again with my fingers into the Vapman (mostly conduction + higher temperatures) and had some really not bad tasting hits (to say "good" would be too much). While this is good to know when the stash is about to diminish, it is normally not worth the effort for me, because it's way past the above mentioned sweet spot
Well, this are my thoughts. Does anyone know more about instruments to measure cannabinoids? I heard of mobile instruments that give out numbers quite fast? Are those reliable? What techniques do they use? Are they affordable?
