I would say that through your observation you should be aware that there is a left or right turning, pull in, drive way and should expect a car to make a turn into these. So you ride being able to stop knowing that the car in front can make a sudden turn. If you are relying on seeing an indicator you may well get caught out by somebody not indicating or leaving one on. A car indicating means nothing more than his bulb works !
So in summary, work the lane to observe the environment, turnings and signage as much as watching the cars for indicators. As a note I worked for Honda and had to have MAC advanced training every year to allow me to ride, covering 75 miles each way to work in Slough from Calne in rush hour.
