Way back in the 70's, if not before, growers with no scientific knowledge observed that crops harvested before daybreak were more potent than crops harvested later in the day. They had no idea that THC works like 'sunscreen' in trichome heads protecting the delicate inner glands and membranes from damaging UV rays of the sun and that each day a small percentage of THC is broken down and lost while doing that job. They only knew that harvesting before daybreak resulted in increased potency.
It only makes sense that some extended period of time for plants finishing in darkness will increase potency to some degree, even if only minor. Even a minor gain is worth taking, isn't it?
Consider what growers do. Most spend money for professional genetics, some paying upwards of $100.00 or more for their beans. They spend money to create sealed light proof growing environments. They spend money for reflective material to increase their lighting capabilities. They spend money, some spend a great deal of money, on their lighting, including multiple lights and light movers. They spend money on different bulbs, including some who spend money on UVB bulbs to increase resin production. They spend money on high dollar 'designer soils' or hydro or aero setups to grow in. They spend money on 'designer fertilizer's and other additives and nutrients. They spend money on ventilation systems to maintain proper temperature ranges and some go so far as to spend money to control humidity ranges. Some people spend money for CO2 setups. Every penny of that money spent is to achieve the most potent herb possible, it is to attempt to squeeze out every last bit of potency that the genetics their strain possesses will allow.
So since it has been known for decades that harvesting before daybreak, and later turning off lights after their last light cycle before harvest so they do not come on again before harvesting, results in more potency and since scientific research has proven that in some strains an increase in THC levels can be as much as 30% is the plants are given a 72-hour period of total darkness before harvesting ... AND DOING SO IS FREE ... why in the wide, wide world of sports would people who pay out the ass to try to squeeze every last bit of potency from their plants ever even begin to consider not doing something that will add at least a small amount of potency, and in some cases a considerable amount of potency WHEN DOING SO IS 100% TOTALLY FREE?
It is totally irrational and totally illogical to do all the other things that people PAY to do but then not do something that is FREE.