Plants in the wild deal with stressors all the time. The wind blows hard and knocks them down. Deer come along and chew off branches. The plants have learned to adapt and deal with these things.
The plant has one prime directive... continue the species. It must finish up those buds, even if it means its own death. It needs to know that when it finally falls over dead, its seeds will go to making the next generation. A plant knowing that the end is coming, will put out an extraordinary effort to complete this process, and in our sensimillia plants, instead of seeds, we are working on resin production and trichomes.
So already I have been sending signals to the plants that their end is coming. The days have gotten an hour shorter. The light itself is beginning to fade. They have already sped up in response to these changes. Some people see a decrease in water usage at the end of bloom, but I see a distinct increase by adding these stressors. My plants definitely speed up at the end.
Next will be the nail and the darkness. The nail is simply a freak out signal sent to the plant right near its brain, that central core of roots right at the base of the plant. There is nothing to equate it to, but the plant clearly gets the message that it has been attacked right at its base and that death is sure to follow. Since we know that plants freak when you even think thoughts of harming them, imagine what a spike through the trunk does... it puts them into a supreme hurry up mode.
Then on top of that, the darkness. I joke and say that they think the sun has gone out and that this freaks them out, but they have no concept of this... they just know that the growing season has abruptly ended. They have no choice now but to finish out, quickly, while they still live.
Experiments have proven to me that these methods all come together to drastically improve the plants at the end. I will start this process at the first sign of amber in the top calyxes, and by the end of a day and a half to 3 days impaled and in the dark, a very noticeable, if not extreme increase in the size of the trichomes is noted, and the amber content also goes up to near 10%.