The point of a close community is to make it serve the members. In general ALL members contribute work since that is how costs are controlled -it is "Self Managed". In the event that someone lacks time to carry their share, usually they hire another Member to cover their duties. It MUST be equitable - Can NOT have 5 out of 20 doing it all unless there is some sort of equitable exchange.
What about someone who does shift work, working 11 pm to 7 am, like a nurse, police officer, chemical plant worker? They will miss most day time meals, since they are asleep during the day. How are their community related duties (cooking, cleaning, etc.) handled? What about someone who is gone a lot, i.e. traveling salesman, long-haul truckers, offshore drill rig worker? They may be gone for a week or two at a time.