Not necessarily….my rh is always ultra low and I don’t run one….and have no issues.
If the rh isn’t spiking during the dark period, you don’t have much to worry about. You can try shortening the dark period so it doesn’t get as cold….before going straight no dark period. I used to run 24/0 and the plants do fine….perhaps slightly smaller, but still healthy. It’s just a waste of electricity, and the plants do better with a dark period, even if it’s a short one.