Never tried it! I know 12/12 works and if it was better to change to even shorter hours, I'm sure it would of been done by more experienced growers and reported. While some experimentating is good, do you want your grow to be the test subject for what has worked so well for so many? Experimenting with one type of fertilzer over another that someone else recommends because it worked better for them is one thing but changing the light schedule is another. I'll stick with what works in this case and not let my little crop be the test subject for millions of plants.