According Edewaard's study, "The Conspicuity Benefits of Dynamic and Static Bicycle Taillights at Night" blinking tail lights on the seatpost provide 3.1 greater distances in recognition (response time) although not nearly as beneficial as placing lighting on one's ankles.
Most of our deaths on the road are from being struck from behind. It is a pretty complicated topic and risk management is never terribly precise. Redundancy helps. Not too long ago there was a terrible rash of ultra cyclists hit from behind and I knew or rode with some of them. I tried to "study" this topic. Some research indicated drivers have but a few seconds to perceive something is out there and then recognize the object as a cyclist. I developed guidelines for me myself that I try to follow. Just sharing what I do to try and reduce risk.
1. On training rides during the day, I run my front light and rear blinky
2. My helmet, shoes, and socks are brightly colored
3. At night I run a steady rear light with other cyclists and both a steady and blinky when riding alone
4. I have reflective 3M tape on wheels, frame, crankset arms, pedals, shoes, helmet, visor, etc.
5. Reflective gillet with extra 3M tape and ankle reflective straps at night
6. I will not ride into a sunrise or sunset unless the road is a very, rural quiet and a broad shoulder.
7. I use two mirrors and test driver's response (are they on autopilot....selective attention) upon approaching
8. I rarely ride long distances in rain on busy roads and never ride busy, narrow roads at night.
9 I used to use the Conti GP4000 reflex tires, the reflective "bead" was astonishingly effective....motorists immediately know they are dealing with a bicycle
10. I always have a spare front and rear light when night riding.
11. I always carry ankle straps and if it rains, even during the day, they go on
12. I used to carry a Spot device and am considering a Garmin InReach currently. Thought about a
Varia but balked at price and battery life.
13. If a long brevet goes into Saturday night in areas of bars, I sleep from around 10-2am at least.
I would be most interested in what steps others take to lower risks.
This study is one of the more realistic ones.
https://vtechworks.lib.vt.edu/bitstr...=1&isAllowed=y
I have developed the need to sleep a lot on long events but being on a fast recumbent, it gives me that luxury. I do not know the make and models of different tail lights when catching and passing other randonneurs but I do know that there is a tremendous variance in conspicuity from cyclist to cyclist and the distances sometimes are not very great. I wish there were better studies out there. This article probably summarizes the overall challenge as well as any.
https://www.bicyclelaw.com/stay-seen...ivers-see-you/