When designing test plans, sometimes it is useful to have control over the duration of execution for the various samplers contained within your test plan. It might be helpful to run a particular group of requests longer than others to see what stress the requests put on the system. This is exactly what the Runtime Controller does. It allows us to control how long its child elements are allowed to run for. This can help shape our test plans to mimic the actual behavior of users in our system. For example, on a typical blogging website, there is far more time spent reading the contents of posts by readers than there is putting up new posts. As a result, you may want the reading flow to execute for half an hour, while the posting flow executes for only 5 minutes.