I got 3 taps on 2 roots (2 on 1, 1 on the other) inside a ribcage of all things, get 30 if it is fully charged, or less sap at a slower rate if the glow is weak.

But I never bothered removing the taps, and they recharge back to full glow again after 1 in game week or few days later or so (guestimate), not sure why but it does. I'll have to test it more. Not sure if anything changed or got nerfed though. Seems to be working for me.