Sure plants love 24 hr light but if u grow indoors with less than 1000watts ur going to want to flower them at bout6-10 inches tall start 12- 12 or be like 6-7 foot tall
I prefer 18/6. It's closer to natural and is less stressful on plants.. so id suggest that if you're using femenized seeds or if your plant is cloned from an outdoor plant you go with 18/6