I would suggest a gauge capable of measuring vacuum levels down to 1um, and would expect that you’d want to stay above 2mm (total guess) if you want to retain any chance of squishing.
At a given tray temp, the vacuum level can tell you how “done” you are.
If I want a vessel dry, I suck on it till 50um. It’s empty!
Do that to your Ice water hash, and you won’t be happy about it.
BYour cannabinoids will still be there, but the solvents the plant used to make them readily available to you is now gone, so is the water I suspect is important to getting optimal yield.
I know water content is critical for every other form of extraction, including flower rosin, so I assume removing too much water has similar effects to removing terpenes.
Certainly my best guess for what’s going on over here: Why wont my ice water hash yield any oil after pressing?