I used this feature all the time in Corel, create a new file, drag a vertical and horizontal guide away from the edge of the page and then zero the ruler to the corner of the guides. The area outside the guides was for dumping elements or testing stuff before I dragged it over into my design space. Im still getting used to AD but I find that using artboards for the same purpose is better, along with Guides Manager (View Menu). Just create one artboard as the design area, the ruler will zero to the edge of the active artboard. Then I create another artboard to the side for testing a dumping elements. Just drag elements across from one artboard to the other. Use the Guides Manager (View Menu) to set all your guides. I set four guides around the edge for the design area artboard first, its quick to do with the Guides Manager. Then from here I can quickly drag in any guides I'll need and then set them with the Guides Manager by just imputing the measurement I want. I very often create a rectangle shape the size I want the guides from the edge and then use with this on the right side to give me a marker to drag the guide line in. Its just the way I do things haha.
