You can really do whatever you want...as long as there is less than 13 or 14 hours of light per cycle the plant should continue to flower, so 10/14 would work, or 13/11 I want as much light during flowering as possible, as opposed to less...so I wouldn't go down on the time any, but it might do something, might make the plant think the days are getting even shorter to hurry flowering, but I think it might just make it take longer to use the light it needs to to make more buds everyday...