It would be very good if there was a built in report showing the last x full system refreshes and how long these processes take. It is possible to build this yourself with the diagnostics data but it will not contain the dependencies as described in this excellent article by Fast Track SA Ashwini Puranik: https://community.dynamics.com/blogs/post/?postid=84fbbaaf-262b-f011-8c4e-7c1e5218b899