I had my toon on for a weeks or so during vegging and then turned them off. I felt like it really was not helping during the grow phase and that it may confuse the ladies into thinking fall is coming and here is why. I had my lights on 18/6 , when your IG light and pontoon light goes turn off, those infra-red like LEDs light up for 5 minutes.
Those are supposed to help transition the plant from day to night time and I was thinking that may confuse them into thinking fall was coming and did not want hermies.
I would think if you have a 24/0 schedule it would not hurt em.