Forget the darkness thing, it is BS, based on one flawed study that turned into an internet myth.
It does not work 100% of the time and/or with 100% of strains.
Botanically, extended darkness would cause a plants metabolism to almost stop and an almost stopped metabolism would not be able to prevent THC breaking down into CBD and CBN, 2 non psychoactive cannabinoids.
Technically, your buds would have less THC and more CBD after extended darkness, therefore I would highly recommend not doing it, unless you want buds with reduced THC and elevated CBD levels.
I prefer to dry trim, this way the moisture goes out through the leaves instead of the buds.
If you wet trim, then all the moistue goes out through the buds, which can then take some of the terpenes away too.
No need to drown your plants when "flushing", all you need to do for a flush is give plain water, nothing else, in normal quantities at at normal intervals. All you are trying to achieve is for the plants to get rid of any fertilizer salts in its system. Flushing is not an exercise in drowning the bejeezus out of your plant, this just causes your buds to become hyper hydrated, which can then lead to mold issues when drying.
Flushing should really be renamed "fertilizer witholding period".
After years of experimentation, I find that harvesting in the morning, about an hour after dawn/lights on seems to produce the tastiest buds.
Hope this helps, Organoman.