Lighting question that just crossed my mind

What about gradually switching to a 12/12 schedule, to imitate the days getting shorter, rather than BAM, and the sudden switch? Theoretically, that should be the best, but is it in practice?

Well, you could. But it throws off a few things, like knowing when you're flowering starts. that "Stretch" aka super growth spurt in the first two weeks of 12/12 is what happens when the days start getting shorter, slowly. You get the same result... and, less headache changing your light every day.