It would be great if projects always stayed on schedule, but as we all know, a variety of factors can cause a project to fall behind schedule. For these types of situations, you will have to work with project management to discuss what could be done to bring the project back on schedule, or if the project timelines can be adjusted.
You may also find yourself in a situation where deadlines have been moved up. This might be initiated by internal management, but external forces may also dictate a change in the project schedule. A new business opportunity may present itself, such as the possibility of a new client, or your organization may be invited to an important trade show and want to demo the software application. When situations such as these arise, depending on the importance and the direction given by management, the team may need to make every attempt to conform to the new time frame.
Even if you have adopted an Agile software development methodology, which anticipates change and helps the team adapt to it, you will need to meet certain project deadlines.