I have tried 20/4 and 18/6 and too be honest i did notice a difference in Trichome numbers on the 18/6 routine, does darkness generate more trichomes? i thought.
I looked into this and Trichomes are the plants natural defences against attack, mainly UV, its like a built in sun lotion that it emits whilst sleeping.
Then there is the theory of putting y our plants into darkness before harvesting etc...
I tried it and it just produced more clear trichs in the 3 days it was in the dark.
Screwed my 'waiting for more milky to come and maybe a bit of amber' thats for sure but all was good in the outcome as they all degraded when cured.
So darkness is definately needed in my opinion for Trichome 'birth'
So 18/6 is what im mainly gonna stick with, but i might experiment with two different grows at both times, same strains, just to see.