As a leader of software development, you must focus on three things: resources (people and money), characteristics (products and their quality) and time.
These three things are the core development of software, and others are outside. Resources, features and time are three sides of the triangle. The changes in any side will affect the other or both sides. If the time is behind, it will immediately affect the feature and resources; when someone talks about what functionality can be added You should immediately talk about time and resources immediately to see you think about it. Therefore, the first priority of the manager is to put this triangle in the heart, use this model to think about the problem, soon, you will find that this triangle is very good for your thinking.
When the time is behind, there are four options: increase time, reduce features, increase resources or three simultaneously. However, pay attention, people can not increase casual. In the myth of the people, the author's point is "Incurable people in the software development project, but will make the work slower."