Private cooks usually work in their clients' homes. It is uncommon for cooks to prepare meals at their own homes because specific laws prohibit this to avoid food poisoning and other issues with food preparation. Personal cooks can also rent a kitchen to prepare dishes and then just deliver them to the client's home.
Because food preparation takes a lot of time, private cooks may spend many hours in the client's home. That means working more than 12 hours is not uncommon. Though some families treat their cooks no differently than a family member, they still have to maintain a little distance and not overstep some boundaries. It is very uncommon for private cooks to dine together with the family.