We need to understand what the product development tasks are in order to execute the product development project. Looking at a model can't tell you everything but it can illustrate the relationship between tasks and the order in which they are performed.
This model illustrates that scheduling phases of development can be challenging, if not impossible at times. The model makes two assumptions: that the instructional products open to improvement and quality reviews are the catalyst for the analyze, design, and develop tasks being repeated. The number of cycles that are performed is dependent upon the project requirements, budget, etc.