Developing an application can be a single person task, but more often, there are more people involved. Change requests and access to the application need to be controlled. It is also important to consider what kind of security is required.
If you are in the enviable position of being able to develop an application from scratch on your own, you don't have to worry about the separation of tasks. Change management is a lot easier too, but there are still aspects that need to be considered.
You have probably come across the question, "How do you eat an elephant?" to which the answer is, "Cut it into small chunks and eat it bit by bit". The same is true when developing a QlikView application. The advantage of having all these small bits is that different people can work on the application at the same time.
However, in reality, there are only a couple of tasks that can be divided easily. Having one...