What is the Date Management tool? 

The date management tool allows instructors to easily adjust all content and tool dates in a course.  This includes discussion board, blogs, journals, wiki and tests.   

You can reuse assessment items as this tools allows you to change due dates and availability start/end dates in bulk.

Why would I use the Date Management tool? 

This is a beneficial time saving tool for when a course has been copied and new dates for the current course can be transitioned across using the Date Management tool.