Until you understand the function of phytochrome, you're only knitting around a forum fireplace talking chit. Once the phytochrome trigger has been put into play regarding the flowering response, any more darkness is just reducing the carbos production of the plant. It's the amount of carbos that drives production. That photoperiod trigger can be as soon as ratcheting down from say......a 20/4 to a 14/10, the forum "standard" being 12/12 for da mutts.
Stop fuckin' around with mother nature people! Veg at 20/4, flower at 12/12 which triggers the phytochrome flag, retain as many healthy leaves as you can until harvest and you'll beat the guy next door every time who is bound and determined to fuk with mother nature.
http://en.wikipedia.org/wiki/Phytochrome
This thread is a perfect example of folks thinking they can push their plants, this time with an oddball photoperiod. Everyone gots to have dar gimmicks.
UB