Even when overtaking...
Its not bloody hard, and when im doing the same travelling the opposite way down a huge gapped chevroned road, and you pop out from behined a car and nearly hit me from the front, I will get up and beat you with whatever debris is left and is solid
Even the car drivers can see you use them (and generally move over a bit to help you, even though its not usually needed), so take a tip, going to overtake, indicate. Really not that difficult to do and makes you far more noticable to all parties (bar ignorent other bikers on a race home who don't look).