The twisted logic behind the kind of thinking that leads to imposed schedules starts with the sure knowledge that any work that the manager is not doing is by definition not important. Not important equates to easy. Easy equates to quick. The other even more illogical equation is that something the manager doesn't know how to do must be easy. Those who need software to make their companies work but don't come from a software background readily fall into this trap.
Some people become addicted to urgency.
The adrenaline rush of tight schedules turns them on. If you're stuck with one of these managers you're probably going to have to probe him for news. Nothing will be worked on until the night before, but if you ask, he or she will probably be happy to pass over the maturing projects. You're in for even more trouble if your executives are fuelled by the thrill of committing their group to impossible deliveries. Here you're going to have to learn to say no.