Unfortunately with project management, things tend to go wrong at the most inconvenient time unexpected changes are unavoidable. However, I do think that when briefing the management personnels about the progress of the project, PMs should try to be as factual as impossible, avoid vague promises and provide reports reflective of the actual progress, and not reflective of the report that the higher up will most likely like to hear. If the project proceeds faster than buffer times are consumed, everything is in the green, which is good for the team and the project. If buffer time is consumed more without real project progress, the project is critical, which is marked red. Whatever the status ( green or red), it will provide an honest presentation of the progress and a better brainstorming of ideas to turn the red status into the green status.