Thanks for your posting. This metric is not yet in TestRail but we’ve added it to our to-do list. You can get this metric by exporting the test run to Excel though and then calculate the sum for the Elapsed column. We don’t have this at the moment as TestRail comes with its own forecasting/summary feature as part of the Progress reports:
The forecast and estimates are calculated based on the estimates, actual elapsed times and average times across the test suite. You can also see the estimates and forecasts for a test suite in the sidebar.
I hope this helps.
PS: I’ve changed your username to remove the full email address so it’s not picked up by spam bots.