On a bright day most bike tailights are of little use. Brake lights on some cars are hard enough to see. But I use them if it is very overcast/foggy/stormy kind of day, then they are not drowned out so bad by the millions of lumens of natural daylight in your vision. I don't worry about how annoying blinky modes are, I've never had another cyclist within proximity to care. And for vehicles a little annoying is probably good. it's not like a bike light or two or three is anywhere near the level of a cop car, ambulance, fire truck, rescue vehicle, snow plow, etc, in terms of annoying.