Overkill is bad only in the sense that you've spent more money or time than necessary. Using more lights or reflectors than you need does not make you less safe. I do not use as much equipment as some people because I think I have enough and don't want to go to any further trouble or expense. Trouble is significant for me, since I ride several different bikes.

On my main commuting bike, I have:

- dynamo powered headlight which burns steadily (doesn't blink)
- dynamo powered tail light, also steady
- battery powered blinky light
- spoke reflectors
- spoke light in my rear wheel, which is a great attention getter

I plan to put reflective material on the bike, too. I will apply it to the frame and the pedals.

Just this weekend, I ironed on some reflective material to my jacket, and I plan to put some on my shoes, too.

I use an eyeglass-mounted rear view mirror, and one reason is to see inattentive drivers who might be about to run me over.

Last night, I rode my road racing bike in the streets in the dark. I had only a battery powered headlight and a blinky tail light. I normally prefer to have more, but I feel it's enough, as the streets here are well lit, the drivers are accustomed to having lots of cyclists in the streets, and traffic goes pretty slowly here.