@zor,
@beiberhole69, these are some interesting points and consistent with what I've experienced. I find my heart rate is a really bad proxy for how high I am. It really only increases if I panick, but other than that stays pretty normal throughout a high.
Also, in my experience, as I've also said before, holding it in for a minute gets me twice as high as holding it in for 10 seconds. The rebreathing technique does seem to outperform holding it in, but by how much? That's what I'm still trying to find out, and I'll post when I know more. (Of course, I realise that what works for me may not do so for others, but I still think it's worth documenting.)
As for holding it in vs re-breathing in terms of the actual mechanism,
@zor, I imagine that although most of the surface area of the lungs comprises alveoli, most of the volume may not. Thus re-breathing may simply just redistribute vapor otherwise stuck in areas where little adsorption would be taking place, e.g. the wind pipe etc. Although pure speculation, I think this mechanism at least explains how rebreathing could work better, though still in the same ballpark as keeping it in, which is what I'm seeing so far. Numbers will follow.
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) and the result is that two hits off my ssv with about 0.06g in Ddave's mod results in a deep rust brown abv weed and substantial effects. One hit is good medicine for anxiety, two to three for insomnia. I've been vaping every day for about 6 years {minus those sad dry spans} and there would be times where I thought my tolerance to be too high (pun!) but I've found myself getting more outta my weed than before.
