I've been doing it lately for higher visibility. If I see someone nudging out on a cross street sometimes I'll flash low/high to make sure they see me. Had a fool act like he was going to cut out in front of me once but saw me at the last second and scared the hell out of me. Since then I've been really paranoid of cross traffic. I've seen the cruisers with the alternating bright/dim lights and they really get your attention. Bottom line is, no matter what you do people just don't pay attention.