Autos and 12/12?

Does an auto have to be grown under 18/6 or 20/4 or can it be successfully grown under 12/12?

Yield will greatly suffer, plants will be tragically small. I tried it when I had some regular light cycle plants and wanted to start off my autos early. Big fail on my part. I grew the same strain using 20/4 cycle once my regular light cycle plants were done. The results spoke (and smoked) for themselves. I totally screwed up using 12/12 on my first batch of autos.

That's kind of what I was thinking after reading in the description of one strain that it said to use 20/4 for the most vigorous growth. It was making me think the shorter light cycle would cause less or slower growth.

thanks hoss!