Clarke said higher THC, I said better effect. He wrote that stuff in the 70’s, I think he would likely say better effect if he wrote it again today. Yes I also do feel stronger UV gives an advantage.
The tropics if you look closer Hawaii for example has traditionally 2 harvests the long season and the short season. The long season flowers closer to 13 hours and was always superior to short season bud.
I like to veg at about 15/9. Plants will usually sex around the 7th node at that regimen, and show resin in veg quicker than a longer regimen.
I might flip them into bud at 12/12 or even down to 10/14, but then raise it up to 13/11 for the majority of flowering cycle.
Yeah yeah, that goes for all drug type cannabis.