Yes, the 8 hours is legal to start legal to finish for the day ... now if something happens and they change your schedule they must make it within 8 hours again, but as long as it's within 8 hours when you start, you can finish it regardless ... now if you hit 16 hours in one day ... well you cannot exceed 16 hours ... so if you're sitting on the ground with one leg left and you're at 15.5 hours, unless you're going 10mi away, you'd better get a hotel :)