Can I modify an existing shot instead of reshooting it?

HOW TO:

1. Let's say you've set up a shot and click Store Shot--and then you later decide you'd prefer a slightly different angle.
2. If you aren't currently in the shot you want to modify, you first need to reload it. 
3. You can do this by scrolling to it in the Shot Preview area (shown in the image below), then double-clicking on the image of the shot you wish to edit.  Alternatively, you can go to the Storyboard Shot Manager by clicking the Tools Menu then Storyboard Shot Manager or by clicking either button labeled SM in the Shot Preview area, select the shot you want to edit then click the Edit On Set Button.
4. In either case, the shot you've selected will be reloaded EXACTLY as it was when you first snapped it.
5. You can then rearrange any objects, camera positions and so on, and re-snap the shot. The new version will then automatically replace the old one.   And that's it!What is this shot Preview Area?  What is it's point?