Single shot could be used but it will trigger at the where ever the trigger is set. So the display image will be random and may not give you much information. Normally you use the single shot along with the Run/Stop function to locate sudden spikes that can be hidden, inconsistent or are to fast to see over time. Like the opening and closing of a switch can produce a ringing effect (bounce) that is hard to see because it's fast and very short term. One of the benefits of a DSO over an analog scope.
Personally, I'm not pleased with my Hantek DSO2D15. The USB crapped out, so I can't save on retrieve anything and can't update firmware to fix other issues. But what do you expect for the price.