Not all HELOCs are set up the same way. I worked for a lender and we only allowed 4 draws and the period was much shorter than 5 years. We found most customers only took 2 draws, the first one when they took out the loan and a second one shortly thereafter.
I’ve just never seen one where the person didn’t pay principal on a regular payment schedule. If the OP set up a $120k HELOC, he could take $100k the first day and pay no principal at all for 10 years if the never took the final $20k? That’s not good lending. That’s 2005 lending, leading to a big crash.