It's personal preference...what do you think is best?....the facts say that cannabis grows more vigorously under 24/0...some claim 18/6 for better root growth.....In Greg Greens Cannabis Grow Bible he claims the "Pros" use 24/0.......
experiment, find what you think works best and makes you happy...and most important, what you feel makes your plant/plants happy.....
but remember the fact....cannabis will grow more vigorously with a 24/0 photo period......cannabis does not need a down time, it is more than happy getting light 24 hours a day.....some will argue other points about having a night during veg, even myself., I didn't want to except it...Jorge Cervantes didn't except it for awhile either,he claimed diminishing returns from 24/0, but he was wrong and corrected himself in his newest book...it is a fact cannabis grows more vigorously under 24/0........
so your choice..
1. what you think is best
or
2. what has been proven to make cannabis grow more vigorously..it's a fact