Those little clip on spoke reflectors do the same job but are more effective from 90 degrees approach angle. Bear in mind that, for the most part, headlights and drivers perception is targeted at the road a short distance in front of their vehicle. Additionally, in a driver's mind something low down in their field of vision/perception registers as *close to* - whilst objects higher up in their field of vision register as *further away*. They're more likely to react to something perceived as closer to them. Pedal reflectors, reflective tape on the front and rear surfaces of cranks, ankle bands - all of these things add to the moving picture.
I use at least two lights both front and rear - as a failsafe. Flash attracts attention, steady makes it easier for an approaching driver to judge your position and speed. Dynamo (hub) lights are set up to run constantly so you can really count on them to be there if/when your battery equipped lights run low.