Is there a way to generate a REPORT for Assignments showing how much time it took to complete each assignment?
You can build an app using Web App Builder that has the table of your assignments. Then you can manipulate the table view and export to a CSV file.
What type of report would you like generated? If you're comfortable with Python, you could generate a custom report pretty easily (csv, pdf, excel, ...). Then you could run that script every night to automatically generate a daily report.
Retrieving data ...