I will be honest, I don't use the turn signals at all anymore. Twice now recently, turning right onto a street, the person behind me was so impatient that they went to pass me (in no passing zones with oncoming traffic) when I put the signal on. Of course, I was starting my turn and had swung a bit out to the left and they didn't bother going all the way into the other lane... The second idiot I followed until I cooled down (he kept doubling back, in that specific hope I assume). I'm not a slow rider, I'm typically going 5 over the limit before I take the turns, and I barely slow at all to make those turns normally. I prefer not to give them foreknowledge of my intended movements now.
I have managed to run with the blinker going for a bit though... I hit the right turn signal when I was going for the horn one time. I must have gone for 5 minutes with it blinking. In that case, self-cancelling signals would have been nice.