Hi Jox,
the experiment I did was based on numbers I had read from cold extractions using rue seeds. Other than that there is no reasoning behind it. If I were you I would experiment with the shorter times as suggested and report back yields. If you find that after 5 pulls you have not reached the desired or expected yield do another one, or a longer one etc...
This could be a really cool experiment actually to see how far the time can be reduced. I suspect however that you will need significantly longer times to soak than when boiling due to the much lower movement of molecules and lower solubility of salts in colder water. I.e. you will need significantly more time than 45min boils.
To reduce this time you could try adding hot water/vinegar instead of cold, in a different experiment, soak for the same amount of time and compare yields.
Personally I don't see the problem with soaking for a few days. You might not get the instant gratification of a fast extraction but it's energy conserving and relaxing to do this extraction

Anyway I'm interested to hear what you get out of the vine. Remember not all vines have the same alkaloid content. Make sure that at the end of your process there's really nothing left in the plant matter.
Buon viso a cattivo gioco!
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energy conserving caapi extraction