I use 3.

i have a blinky on the loop on the back of my bag.

i have a blinky mounted on the seatpost.

i have a landing light mounted under the saddle which I run on steady. It is actually a Gemini Titan, that used to be a headlight, I got a red lens for it (shaped) and run the 750 lumens on steady along with the two blinkers.

the blinkers are both Blackburn Mars 4.0 -1 watt LED's.

i'm bright.