Originally Posted by
noglider
I think whether it saves you is unknowable. You can only know if it DOESN'T work.
Decades ago I stopped at a stop light that had just turned red, was riding a motorcycle that I had commuted on for 12 years. The guy behind me was sure he could make it thru the light before it turned red if he floored it. Totaled the motorcycle and I had trouble walking for quite a while after that. If on a sunny day someone does not see the bright brake light on a motorcycle that weighed about 350 pounds, I doubt a bicycle with a flasher will do the job either.
But we are in a world of averages, and on average you are more likely to be seen in daytime with a flashing taillight on. Nothing will prevent it, but there are ways to minimize your risk.
I did my first trip with ACA in 2012, on day one I rode with a flashing taillight, none of the dozen other riders did. At the end of the week, apparently two others had noticed my taillight, they were using theirs too. Things have really changed, now I even see flashing taillights on gravel rail trails where there are no motor vehicles (other than the e-bikes that pretend to not be motor vehicles).
If I had not been run into on my motorcycle back in the 1980s, I am not sure if I would have been one of the first to be using a red flasher in daytime or not. That experience likely had a part in my decision to use one.