Some years back, a colleague and I had a discussion with our guv'nor about whether when driving you need to indicate when there's no other traffic about. We were / are of the view that it should be an 'automatic habit' regardless of traffic conditions. He felt that there wasn't any point, suggesting that it needed concious effort to decide whether to indicate or not. 
As my driving instructor hammered into me in 1972 - 'mirror, signal, manoever - !'
Your thoughts - !

As my driving instructor hammered into me in 1972 - 'mirror, signal, manoever - !'

Your thoughts - !