Reflective clothing is good but does not light up unless a headlight is reflecting back. So no help in a rear view mirror or for cross traffic. You need both. The reasonable rule for lights is if the light is as blinding as a car headlight, set it steady. If it's a lame teeny LED that would be lost in a sea of car headlights on steady then set it to flash. If there are many many street, store and car lights set the light to flash to be noticed. On a side street that is poorly lit and there are few other lights steady is good.
Yeah I agree but on a city street at night there is ambient light washing over everything so reflective stuff still lights up in any direction. When viewing cyclists from inside a car I've noticed it's always the people in reflective clothing that are the most visible. People in dark jeans and a hoodie with a blinkie are barely there in comparison. While you're at it sure throw a couple of blinkers on your bike but I don't see any reason why they have to be the brightness of a small star.