The iterative approach of SCRUM provides 3 key benefits to the organization.
- Sets a Rhythm: It helps the organization to quickly establish an internal development rhythm, and all cross-functional teams begin to work by this rhythm.
The development teams gets into the mode of planning and delivering a release every month with new features, the business analysts and product owner gets into the habit of ensuring that the highest priority backlog items are completely well-defined in time for the next sprint, and the customer learns to expect a new release every month, with added functionality that can be objectively seen, commented upon and accepted.
Month after month, the rhythm is maintained, and soon management is able to identify key metrics for which data can be collected, monitored and fine-tuned.
- Focuses on tangible deliverables: The waterfall model is also broken into multiple phases, but the deliverables at the end of each phase are intangible artifacts, such as requirement specifications, design documentation, project plans, test plans, untested code, etc.
The only tangible delivery ever made in the project is when the product is released to the customer. no doubt, there is value in all the various artifacts generated at the end of each phase in the waterfall model, and indeed, many of these artifacts are also created and used in iterative processes.
However, they are merely an aid to the development effort and nothing more. A customer has no use for a design document, nor will the company's share price go up because a project plan is complete. On the other hand, being able go to market with the first version of a product ahead of the competition, or being able to achieve faster turnaround times for bug fixes and new features will definitely go a long way towards keeping customers and shareholders happy.
An iterative development model keeps everyone focussed on the software as the ultimate deliverable.
- Emphasis on timebound delivery: The 3 main factors that impact the success of a product is features, quality and timeliness, and planning a project is typically an exercise in achieving the right balance between these 3 factors; one factor cannot be changed without having an impact on at least one of the others.
The key difference between a waterfall-based project and an iterative project is that the former has a greater interest in keeping the feature set intact, while the latter is time-bound. That is, an iterative project places the emphasis on making a release at the specified time, even if it means shipping with one less feature.
A company might, for example, have a policy to release a new version of their product every quarter. With such a policy, the organization can confidently make an announcement to their customers that the next release will be made on a particular date, with a certain set of features. All cross-functional teams such as development, QA, business analysis, technical writing, etc are in tune with this policy, and work towards maximizing the number of features and bug-fixes they can complete and integrate in time for the next quarterly release.
Now, if there is a delay in one of the features, or something changed to make a feature redundant, the deadline is not affected. The organization can still make a release on the announced deadline, perhaps with a feature or two less. The delayed features are subsequently released in the next quarter.