I do 4 to 7 hours of darkness depending on the dimming options/minimum distance of light.
Its always about DLI (daily light intake) which I don't compromise, ever. Meeting the climate standards for it (temp/humidity - VPD)
For seedlings 24/0, DLI <15.
For vegetative state 20/4 - 17/7, DLI 20-40.
For flowering 12/12, DLI 25-40, up to 65 with co2.