I just re-read through this thread.... of course beginning at the beginning. I think the OP made an excellent point about diminishing returns... although I am not sure that was his actual intent. I wear a helmet even though it is likely over-kill it is also a lot of protection for very little cost or effort. Dusk-dawn and rush hour traffic is when I add a rear light. I add a front light.. at night.

I wear cycling specific clothing which is often bright and has reflect trim. I might consider a vest under the right (wrong?) circumstances.

Selecting my equipment is pragmatic decision making. Processes or routines added for a "feeling" of safety are merely superstition. A go-cam or favorable horoscope will not make my cross town ride through traffic any safer. Besides being a form of transportation.... bicycling is a sport. One of the early lessons of sports is setting aside or working through fear. We can't bubble wrap ourselves and still pedal. We have to accept that yes we are breakable.

Bicycle vs automobile accidents can make for serious ouchies for the cyclist. But the alternative isn't layers of superstitious practices and processes. The only real alternative is an acceptance of the obvious risks.