I don't need to read a book.
Anyway, it's interesting that you would bring up medical. Some of the compounds that provide the medical effects people are seeking exist in higher amounts with a fully ripe plant. It's not just about THC and it's psychoactive effects.
Dispensary weed is grown for a profit. Much of it is harvested sooner than it should be to reduce costs and get the product to market to be sold. Lab results showing THC levels only come from a small sample submitted and do not necessarily represent the majority of the crop.
In Oregon what's called a "field sample" is used for "batches".