This is old advice from the old ancient out of date Cervantes book... "its normal and desirable for the plant to die off before harvest."
There is a reason pot today is so much stronger than it was in the 70's... we have learned better methods.
I never read that book.
Are you positive cannabis wasn't as strong in the 70s. I was there.
There are many strains still going strong from back in the day.
Most of the problems are in the fact that back in the 70s we were getting landrace Sativa that was grown near the equator with a growing season of well over 100 days. We dont have the patience these daze.