I live at 8.8 degrees north and never heard of that. Native sativas are very long flowering down 16 to 20 weeks, we don't need more time. The sativas at least the ones in the ground under the stars are very light sensitive especially to the length of day since here there is about 50 minutes difference between summer and winter solstice. Flashlights and full moons are hard on use especially the ones at altitude, 2000 meters here.I've heard of growers that live closer to the equator and experience close to year round 12/12 will flash their plants everynight with a flash light to delay flowering so they can get more veg. growth in before budding. Just a thought