Same here. I got by fine with a 110-lumen Fenex LED for several years. Went to a 500-lumen Light & Motion Urban 500 a couple of years ago, but I usually run it on medium and low (250-125 lumens) to extend the run time. I also have a L&M Vis 360 helmet light system, which adds another 120 lumens on high, 60 on low (and I usually run it on low). So my typical setup is about 300 lumens total and it is all the light I need for commuting from the suburbs to downtown. I turn my lights to low when it gets bright enough outside that I am using them to be seen rather than to see. People who claim to need 500-600 lumens minimum must have night vision much poorer than mine.

One point I would mention is that you actually need a brighter light when riding in areas with a lot of ambient light from street lights, signs, headlights, etc, than when riding on dark roads. When riding in dark areas, your eyes adjust and open wider, so a given headlight will seem brighter. When riding in relatively well lit areas, the opposite happens and your light gets drowned out by competing sources.