Best Light Schedule for Autoflowers?

Depends on your light. If it is not powerful enough to provide 35-40 DLI over 18/6, that is a good reason to give more hours of light. Even if you impinge on a dark cycle -- in some cases it may be better to give more light than have a dark cycle, but that would relate to an underpowerd light and nothing toward high end of that factor. e.g. increasing from low 20's DLI would probably benefit even if it was 24/0. ... but trying to bump up from an existing 30+ DLI probably would not be worth 24/0. Not saying that is break-even point but the poitn at which math probably isnt necessary and easily see it in the results. DLI is the key.. not hours of operations. DLI takes that hours of operation and size of garden into consideration already. It is the apples to apples metric you want to use here. You want a light that can give 35-40 DLI. if it takes 16 h or 20h to do it , it matters not. The yield will be no different as far as you can tell.. some fraction of a percent that doesn't eclipse normal volatility of results, maybe. i.e. irrelevant differences that you can't even be confident are caused by the options available for hours of operation. read the wiki. it explains it better than i can. Daily Light Integral... the peanut galery's perception of light is incredibly flawed. becareful whom you listen to. stick to reputable sources like bugbee on youtube, cocoforcannabis, research papers etc.. not word of mouth nonsense of forums and the typical weed sites.. everything i said can be verified, that's the difference. So, the only context in which you'll see abenefit by giving more hours is if it is an underpowered light in the first place.. a poorly matche dlight relative to garden size etc etc... human error/misunderstanding related or simply the best light someone has available that is underpowered with no other options.