If you are in a position where you manage people, you ought to be careful about what you say to your subordinates. My ex-colleagues from another department had the misfortune to work under a manager who had these words of wisdom for them with regards to a project that was threatening to overrun the deadlines: “Don’t ask for a deadline extension unless you have worked 24/7 and over weekends as well.”
Perhaps that manager was misguided into thinking that the people under his charge will either be scared to the extent that they will work harder, or they will not be scared but still soldier on anyway. Unfortunately, he should have realised that people can also choose to walk away, and once that happens, domain knowledge and expertise goes with that same person as well.
Managers who take on the role as people-managers should realise that all their staff always have the option of tendering their resignation regardless of the importance or progress of a project. I’m just thankful that all the managers I had to report directly to so far in my career have not made such an unreasonable demand as the aforementioned manager. Even if deadlines are tight and cannot be moved, there are kinder and gentler ways to bring the message across.