Each area of the software does have the ability to customize
workflow. So requirements can have a different set of statuses and
workflow than test cases and those can be different than defects. It
sounds like you may be thinking that the workflow is the same in each
of those areas but it is not. We have a movie that explains workflow:
http://www.pragmaticsw.com/GuidedTours/Default.asp?FileName=Workflow.
Let me know if anything was unclear. Thanks!