This is partially my thought process and why I think 18/6 with enough intensity and a custom spectral recipe is the key. With them being stretched with long internodes it sounds like shade avoidance but I'm fine being wrong lol.
I think blasting a high ppfd with a static spectrum is why BigSmo has a winning recipe with his autocobs with autoflowers whereas if spectrums could be tuned a higher ppfd in a shorter cycle could be achieved. Plants do the most growing in the dark, not everyone runs 30+ watts so I can see a less intense yet longer cycle being beneficial.
Let's take your theory of light cycling, mix in tunable spectrums from 2700-6500k, high ppfd or 30+ watts per sqft. and I believe magic might happen. Bridgelux, California Lightworks, Samsung, Osram, and
@Scynce Grown all produce tunable spectrum lights. Ruderalis doesn't receive a static spectrum like 3000k for 24 hours a day, could possibly be the reason people believe outdoor weed is superior to indoor, rather it gets a a spectrum of spectrums throughout the day and season. Surely that influences terpenes, hormones, auxins, etc.