How does a project get to be a year late? . . . One day at a time.
As work slips and the project deadline looms, engineers work very hard and get little credit. The idea of rigorous testing is squeezed out in a mad rush to get something passable out the door on time. Bad estimates are a prime cause of this software circus. They foster managers' incorrect assumptions about the difficulty of the development work, since they have no way to know the schedule was incorrect in the first place. When we make an estimate, it is therefore essential to get it right.