This reports how long, in milliseconds, the most recently completed test iteration actually took from start to finish, which an admin can compare against the expected duration, namely SLM count times SLM interval, to sanity-check whether the test ran at the pace it was configured for. A session configured to send 1000 SLMs at a nominal fast interval that reports back a duration far longer than that math predicts suggests the device itself experienced delay or contention while generating the test traffic.