Blinkers are stinkers. I don't believe lights have much use in the daytime, but at night, sure. Dusk and dawn are tricky, but it's best to use them as well at those times, since bad visibility and drowsy drivers/cyclists is a bad combo. I used to be more lax about it, until I got my drivers' licence and had a few close encounters of the third kind with ninja cyclists. the difference a small light makes is enormous.