Does Uber have a policy that their drivers only work for a certain stretches of time or do the drivers pretty much just make their own hours? If the accident w

Does Uber have a policy that their drivers only work for a certain stretches of time or do the drivers pretty much just make their own hours? If the accident was a result of over-exhaustion or something I could see a case where Uber would be liable for not policing strict rest periods for drivers.