These are the ways you can keep track of workflow states...
On the content, the current state is shown in the workflow status bar
A filled circle means you as the current user, are assigned to a content review in that state.
Learn more about the current state in the workflow popup
See state transitions in context of other actions in the Activity Report - Content
See current pending document actions for tasks and approvals in the instance for the current user in the My Comala Document Documents Action Report in the user profile
Get a summary of workflow states for all content in a space using the Document Managment Report
Add your own reports:
Use workflow filters in Confluence search:
Requires Confluence 5.8 or above.