Legal Question in Employment Law in California

Indefinitely. However, unless you are salaried and fully exempt from wage and hour laws, the most they can work you without kicking in overtime (regardless of the number of hours which is a different issue) is 12 days. On day-13 and every day after that without a day off, they would owe you at least time and a half, and eventually double time (though they may owe overtime sooner than that depending on the accumulated hours worked). If you are a fully exempt, salaried employee, however, they can work you every day without a day off until you quit if they want to.