Isn't the answer to the OP question based on how much is consumed? I've seen folks post on here that they only drink perhaps two or three bottles a week, yet there will be some who drink most days if not every day, don't stick to just two or three, their partner drinks it too, they entertain, and they give it away as well. And some only brew 5 litre batches whilst some are almost on an industrial scale. All of which means there's a potentially a huge spread of answers.
All I'll say is I tend not to brew much in the summer (no brewfridge) I brew in batches since I re-use yeast, and I try to maintain a carbing and conditioning stock of between about 50 to 90 litres of beer.