Give the lights/ballasts a break? I'm not sure. It's probably something I read on one of the hundred posts I've read about how to run your lights and it seemed best to me for whatever reason. I think the idea of providing the plant with some period of darkness seems like a way to emulate something that happens in nature that could have a beneficial effect. wtfknm.
I plan on switching to 18/6 once I hit the veg stage (which I'll be looking for help to discern).
Edit: I found the source. It's from the documentation for my grow lights.
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