Hello Ashwin, this is a great observation. There are several processes that could trigger change requests without the need to observe Approved Change Requests. For instance, the Execution Process Group commands the greatest amount of project work, effort, and resources. Likewise, the resulting planning and rebaselining from this process group necessitates changes i.e. reconsolidating resources, changes to resource productivity, schedule changes, budget changes, and changes to unforeseen risks.
These fluctuations will normally alter the overall project management plan in some way, whether the impact is favorable or negative. A project manager and the project team should analyze the deviations impacting schedule, resource, scope, etc. The analysis will ultimately provoke change requests that must be assessed and evaluated. When change requests are approved the project management plan and various baselines need to be adjusted as a result.
Approved Change Requests still need to be analyzed and evaluated as the project is executed; this is why processes like Control Quality require the implementation of analytical tools, such as the seven basic quality tools, statistical sampling, and inspection. Perform Integrated Change Control must follow once new change requests are created as an output of Control Quality.
Did I explain that well enough? I wanted to make these examples as general as possible so everyone could relate and understand them. Please let me know if you have anymore questions on this topic and I'd be more than happy to help.