It's true that no amount of lighting guarantees safety. One hazard is that they may see, but not comprehend. Yesterday on my way home, I was getting ready to make a left turn (across the path of oncoming traffic), and a car was coming toward me that had only one headlight working. It didn't really "compute" for a moment. How far away it was, where on the road it was... the working passenger-side parking light finally gave me the divergence cue once I picked up on it, but in downtown traffic in the dark, it took a moment.

This "what is it?" perception problem is part of the reason I go to great lengths to add "context" besides lights, such as:

• the invaluable reflective legbands (the motion attracts the eye and gives the "human being" cue)
• reflective vest
• reflective tape on the bike frame, crankarms, and wheels
• reflective tires
• a jacket with reflective tape down the arms (although I need to make a new one, the zipper's failing).