Hey Apkesha, IsStopRequested() method is typically used within a Decision stage usually after a case in the Work Queue is completed and before the Get Next Case is made. Placing the Decision stage at this location causes the process to complete the picked up case as we expect it to complete without abruptly terminating the case.
At any point there can arise a need to manually stop a running process. So for that, there are two options when you right click a process that is running in the Control Room viz. Immediate Stop and Request Stop.
When you click on Immediate Stop the process will stop wherever it is running at that point. It is similar to the Stop Selection button shown in the Control room near Show Session Variables. Whereas if a Request Stop is made, the process continues till the above Decision stage is reached and then takes the route of the 'Yes' branch of the Decision stage before it finally stops due to the 'End' stage placed there by the Developer. There can be log out and closing of applications performed between the Decision stage 'Yes' branch and the End stage.