Courtesy and Good Manners are excellent quality and should be your normal default. However, there is a point that they can push you into dangerous territory and potentially make you a victim. Learn to understand when and where you should shift your behavior in favor of safety.
Situational awareness is a topic that gets a considerable amount of attention in our Comprehensive Situational Control (CSC) course. Rightfully so, as good situational awareness literally can mean the difference between life or death in a number of critical situations.