I believe it unwise to do so. After three days, your plants metabolism would be basically stopped, meaning she would be on the verge of dying. Also, due to the almost stopped metabolism, I would be very worried about all of the cannabinoids, terpenes etc being highly degraded and in the process of rapidly breaking down due to virtually zero energy being produced by the plant and the plant being unable to maintain over all general health. Your plant would basically be "comatosed" after three days in the dark and I personally can see no real benefit or biological reason why this procedure would have any possible and tangible benefit on the quality of the flowers. I would be very hesitant to recommend this technique and believe it is an "old wives' tale" that should be left to go the way of the dinosaurs. I can see too many negatives toward general plant health and condition rather than be basically "torturing" her with 3 days of "suspended animation". I always like to harvest just as the day begins, about an hour or so of light time, this way I believe the plant is "fresh from her "sleep" and her metabolism is just starting to get going and her cannabinoids, terpenes etc are at their freshest, and before any "protective" activity has begun for the day ahead under light. I would think after 3 days in the dark, the plant would be "freaking out" and very well past her prime condition. Good luck with whatever you choose, but I personally wouldn't leave my precious babies freaking out in the dark after 3 months of tender loving care to risk all those prime quality flowers for no valid scientific reason.
I would be harvesting my girls when they are at the happiest and healthiest, first thing in the morning and not after 3 days of zero metabolism.
If you do want to "torture" them with 3 days of darkness, water them before, as there would be no point to watering them after being in the dark as their metabolism would be almost running at zero. Also, if you put them in the "torture chamber" with dry soil/substrate, you risk even more breakdown of cannabinoids and terpenes etc from the double stress of being dry, compounded by the trauma of being in the totally unnatural situation of extended darkness. Hope this helps,.... Organoman.