a slow reduction in light toward the end of flower could finish your flowering a little sooner, this could equate to a reduction in yields.
I believe DJ Short was on about his blues or was it ww ?
If your doing 18/6 in veg, 14/10 will switch them. Do this the first 2 to 3 weeks. 12/12 till last 2 weeks. 10/14 last 2 weeks. But watch closely on the trics. At 10/14 they finish faster. But get harder.