My experience with autos is less light time = less or more larfy buds. Thats just me. I’ve run Mephisto, Mendo 20/20, and Night Owl. The one time I ran an auto on 12/12 with some photos yielded the larfiest buds of any auto I ran.
i was just in a discussion on another thread on this. 20-24 hrs is what autos need, depending on the variety, for maximum yield. one person said they ran 20-4 unless the plant started looking bad and then cut it down to 18-6. i’ve never ran them myself though.
I’ve been running my autos on about 15/9, and included some in a 12/12 run twice. I think the 12/12 slowed them down, but didn’t notice any other issues. I’ve got the light intensity on the high end. I’m not a perfectionist so this doesn’t mean others aren’t right about what’s ideal. Right now the light leaks into my bedroom, so the plants have got to sleep when I do . When I get that corrected I’ll probably run 18/6 the full grow. I mess up my timers about half the time when I try to change them, so frequent variation is not for me.