I've never done anything short of 24/7 myself. I can't see where it wood makes alot of difference. Might be a good thing for peoples dealing with heat during peak temp hours? Or peoples cloning in the veg tent?
Funny I veg with the door open to my veg tent, even with lights on a 20/4 schedule.
I do know that's not a proper way to veg a plant and if my mentor was here,, he'd slap the shit outta me,, plants really do need a good nights sleep,, and they do grow at night. My mentor preached that,, he'd say the huge fan leaves, well all greenery on the plants spend all day processing light into sugars,,, then at night,, they burn up that sugar growing at night. We use to grow in this huge barn/ greenhouse, 3-400 plants at a flip, and I swear you go in there at night and you can hear plants grow. Alittle noise here and leaf move there. After 15 minutes laying there,, you hear all kinds of things going on. Yea sure we were smoking our product,, and other things,,,, but was alot of noises in there,, from plant growth.
He was also a big fan of spanking his plants,, well everyone's plants. He'd carry a rolled up newspaper and pop the mainstem on every plant in the row. Stimulation promotes growth he'd babble. If you asked twice he'd hit you with it...