For the active primary fermentation = NO. For secondary fermentation and bulk aging you want 0 head space.
Reality is an illusion that occurs due to the lack of alcohol.
Give a man a beer, he'll drink for the day.Teach a man to brew, he'll be drunk the rest of his life.
I have 8 carboys, 8 cornies, 5-1 gal jugs, 200 wine bottles, 10 cases of beer bottles and a nice assortment of flip tops....My goal is to keep them at least 50% occupied