none of this is necessarily directed at anyone in particular lol.
i went to 16/8 vegging, and ill never go back to 18 personally. I can give like 25% more intense light on 16 vs 18 without any burn, and i can get tighter node spacings, and when i flip to 12/12 the nodes dont space out as much during the stretch, the plants across the board are easier to manage and stack into colas better and all my vegging plants just feel happier at 16 in a way thats hard to put my finger on.
fwiw anyway. Ive only experienced benefits going to 16/8 over 18/6. not a single con so far. Its actually the only growing decision ive ever made that only has benefits. The only reason i use 18 or 20 these days is if im trying to veg a plant under less then adequate light intensity.
Random PSA: If you see magnesium stripping on your plants from light intensity, thats not light burn, that doesnt mean you need to back your lights up, that means you need to feed your plants heavier. The more light you give your plants the more they have to be fed to keep photosynthesis and sugar production from outpacing the availability of minerals in the soil. You can give happy cannabis light so intense it literally bleaches the tissue white without burning it, as long as the plant is thriving well enough. Cannabis can take more light without burning then most cacti can. If you cant feed your plants heavier in that context without nutrient burn, then you need to dial in your soils/NPK/micros or overall ratios for that plant a bit more. Actual light burn, nutrient burn, and immobile nutrient deficiencies can be almost identical to each other on some plants too. What determines which it is on many plants, is just keeping track of variables and context that led to the expression of the problem you are seeing.