There is always a specific point where there is indecision about whether to stop or keep going when the light turns yellow.
- Stopping means hitting the brakes hard, possibly causing an accident due to someone rear-ending you.
- Proceeding means you might shave a bit of the red.
Shaving a bit of the red is generally not going to cause an accident because it takes time for cars to accelerate and get going. There is also a dead-time between one direction turning red and the other turning green. However, as someone who was nearly rear-ended for stopping at a light because I had to brake very hard, I'd much prefer to proceed than stop in these cases.