usually i don't think , but when it is fog i turn them on because i like it that is all, and it is my opportunity to do this.
it looks like we are in a festival, then while stopping at the signal u start to think why the car in front of me its signal lights duration more that mine so i start calculating the difference between the sound in my car(tick...tick..tick...) and his lights.

this is usually what happen when i think :P

D**n i forgot to turn them on today.:(