I have always found a limitation in the way Draw and Designer handles contours. There is no way of selecting the alignment for the contour. For example if you do an ad and want to have a frame around it and you set it to 4 points, the resulting frame will only be 2 points since it will always have its center over the page border and the outer portion of it will be cropped away in the PDF export. Any rounded corners will also look crappy for the same reason. If you specify a bleed to capture the whole outline, the ad will have the wrong dimensions.
I now had to work with InDesign for a job and although it is cumbersome in its object handling, ID has got a stroke palette where you can specify stroke (contour) alignment. This is long overdue in Draw and I expect it at the latest in the next version.
Here's how it looks in ID: