I did a series of semi-scientific empirical experiments using my volcano hybrid with the whip attachment and OG mighty to characterize cannabinoid delivery as a function of time with some minor investigations into the influence of other factors like amount of material. Lacking analytical equipment for quantitative measurements of cannabinoid content of samples, I instead relied on visual observation of vapor density and A:B comparisons of the perceived psychoactive effects of different sample sizes. One key tool of observation was the collection of ABV produced by a series of consistent experiments using dosing capsules, followed by consumption of the resulting ABV in the Volcano's full size chamber and observing the amount of psychoactive effects.

I found that vapor production increases rapidly within the first minute, reaches a plateau and is roughly constant afterwards. This plateau is up to around 10 minutes, depending on the amount of material and strain. Even with small quantities, this period seems to have a minimum of around 5 minutes. The mighty is subjectively better at extracting very small quantities (~1/4 of a dosing capsule) compared to the Volcano. Particularly pungent strains, such as locally available CBD-heavy products tend to also have a longer plateau phase. I didn't study abort any experiments during this phase, so I am working under the assumption that cannabinoid content is roughly correlated to visible vapor production.

After the initial plateau phase, visible vapor production progressively decreases. Exhaled vapor is no longer visible well before vapor production ceases, as vapor can still be observed from the mouthpiece (Or nosepiece, in my usage pattern). It is this phase that I sought to better characterize, as the presence of visible vapor from the device indicates that desirable cannabinoids still remain to be extracted. This visible vapor production remains even as long as 30 minutes after the plateau phase (using the volcano)

My initial estimate is that this 'ramp down' phase follows a familiar halflife exponential decay curve. To measure the decrease in potency, I collected the ABV from several dosing capsules, all having been extracted for a similar amount of time, 15 minutes, 20 minutes or 30 minutes. The resulting ABV was then extracted a second time using the Volcano full size chamber. By comparing the number of dosing capsule quantities to achieve a similar psychoactive effect, I could qualitatively compare the reduction in potency of the samples.

As an example, after the full 30 minutes of extraction (The automatic shutoff timer of the Volcano), the ABV from 6-8 capsules subsequently loaded in the Volcano full size chamber produces a similar psychoactive effect as a single dosing capsule of fresh material. A number of successive experiments with shorter times produce qualatative results consistent with a halflife or exponential decay curve, with a time constant guesstimated around 5 minutes. That is to say, every 5 minutes, there's half as much usable cannabinoids remaining, so that after around 30 minutes there's about 1/8 as much usable active ingredients remaining as in the original fresh material. At this point, continuing extraction takes increasing amounts of time for less benefit. Personal experience is that 15 minutes is a practical maximum, after which little increase in psychoactive effect compared to a longer extraction.

These experiments are consistent with the general usage patterns reported by other users

TL,DR: until exhaled visible vapor and fragrance ceases, maybe plus a few minutes. More than 15 minutes is pointless.