I'm just using the VS for the most basic video editing and most of the time... creating video files, so I don't use the PAUSE DURATION feature that you are mention.. However... I looked up your question and here's the what PAUSE DURATION is..
Pause duration determines how long your pause will be in the designated area before the clip exits the screen. If you applied motion to the Overlay clip, drag the Trim markers to set the Pause duration.
Here's another one... Pause duration handles to specify how long the text will pause after it enters and before it exits the screen.
So I guess... Pause Duration is best when you're creating a slideshow and you want to keep focus on a particular frame or control the way text enters and exits your screen.