I started riding a couple years ago with bright lights on all the time. Three of my bikes have generators. On my fourth, a Bike Friday Tikit, I use battery lights (lots of them). The first day riding home from work on the Tikit, I witnessed a head on collision between two cyclists. A young woman on a heavy mountain bike came around a blind corner too far to the (her) left side of the trail heading straight toward me. I was on the far right side (my right). I was using a helmet light & another light on my bars even though it was bright & sunny outside. She saw me, swerved to her right & plowed head on to a young guy to my left. I don't know if the lights saved me from that, but it probably helped her see me.