I just use them when docking, I also carry handheld 12V spotlights for 'spotting', but I do see people cruising along with ocking lights on as if they were 'headlights'. I From my living room I can see those folks all the way across the lake - crazy. Obviously, everyone relies mostly on night vision when boating after dusk, one good blast of docking lights could mess up another boater's night vision for at least a few minutes. Way illegal as mentioned. It's funny, I comment to my admiral so often on this or that violation as we see them occur, that she jokingly calls me a 'junior lake policeman'. These occurances seem so constant, that it makes me think that Boating Safety Courses or certificates should be mandatory in order to purchase, rent, or operate any watercraft. Either that or a brain.
Back on topic, the nice thing about docking lights is that it frees up both hands for steering and throttle when docking at night.