From my experience, once a plant is in full flower, I mean Bart Simpsons )I call them) all over about a month into flowering, you'll need a lot of light to mess things up...like 18 to 24 hours of light for it to reveg. Folks mention foxtails, which is also possible, but in my opinion, anything less than 14 hours of light per day is fine. Although, when in flower stage, the more darkness the better up to a point, as it stresses the plant into producing more resins and THC and finishing a bit earlier with extra darkness. Almost plant psychology...almost.