As you go through life you develop experience and you let that experience guide you. My experience is that riding a bike is very different from driving a car, and that it is possible to bike up to an intersection, look for traffic, and cross safely even when the light is red. Around here, there is also zero risk of getting ticketed for doing so. I always yield for red lights and stop signs, but I only stop when necessary. Why would I sit in the middle of the street for no reason when I could be going on my way? I can't recall ever having a close call when I've run a signal, but I've had a few close shaves with cars that ran their signal.
The city of Toronto did an excellent study of car-bike collisions -- the only reasonably scientific and objective study I've ever heard of. It's at
http://www.city.toronto.on.ca/transp...ion_report.pdf .
One of their conclusions:
"For example, while there may be a perception that many cyclists recklessly disobey stop-signs and traffic signals, our analysis shows that less than 3% of collisions involve a cyclist failing to stop at a controlled intersection. Targeted stop-sign enforcement campaigns along busy cycling routes may result in large numbers of tickets being issued, but their effectiveness in improving traffic safety is questionable. Enforcement that focuses on driving and cycling infractions that are found to contribute most often to collisions and injuries can be expected to yield better results, in terms of improving safety, than campaigns that simply target infractions that are easy to enforce."
Finally, before you get too passionate, go sit by a stop sign and count how many cars actually stop completely. If it's more than 10% it's exceptional. Washington, DC, now has photo enforcement of red lights at a few intersections. The cameras average over 100 violations per day per intersection -- and violations are down 60% since the cameras were installed. Because the cameras are automated, they give the motorist the benefit of the doubt, and don't start shooting until several seconds after the light turns red, so the real number is higher.