As for having lights on in bright clear sunlight: the brighter the sun, the harder the shadows, and the less your eyes are adjusted to see into the shadows. Taint rocket surgery. Generally there isn't that much point to it at mid day, but there are such things as spots of country road that are pretty much tunnels through overhanging trees. The more you have a habit of leaving 'em on, the more likely they will be on when it matters.