Weaknesses of the waterfall model

In classical project management, the project plan helps project managers execute and control the project’s phases. A project plan typically includes the costs, as well as the project’s scope and a schedule. Further, it defines milestones, activities, deliverables, and resources.

Change management isn’t integrated

The attitudes toward the role of the project plan are very different for defined and empirical teams. In a classical approach (like the waterfall model), the team works with a highly defined approach. It tries to keep as close to the project plan as possible. In an agile team, which uses an empirical model, the team regards the project plan as more flexible.

Errors and customer feedback are identified too late
One of the greatest weaknesses of the waterfall model is that customer feedback is obtained late. There are often errors identified in the development process, which is a late stage and where changes are costly to implement.
The waterfall model doesn’t incorporate any feedback loops. Customers provide feedback only after testing, once the product or service has been completely developed. At this point, it’s too late for the feedback to inform the main development process. This is the same with cost-intensive manufacturing errors. Errors may be noticed only during the testing phase, during which the product is inspected fully for the first time. Teams often decide they can implement only the most necessary fixes because adjustments at this stage can introduce bugs and delays in deployment.

Changes are costly
If the customer decides the requirements change during the course of a project, the associated adjustments are costly and time-consuming. This is because change management isn’t integrated into the development process. The result is that changes may have to be handled through separate new projects.

When using a highly defined model, the project plan prescribes the budget, scope, and schedule of a project. This model is carefully planned and project stakeholders have to approve it. They are responsible for ensuring the plan complies with all their requirements.
The project team follows the plan as closely as possible. In this model, project leaders need to determine how changes will affect the plan when a change is requested. A project may even be halted while change management processes are implemented.

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