When columns meet up at nearly right angles, there can be a gap that forms as the fabric is being ‘parted’ in two opposing directions. Sometimes you can overcome this by stretching the later object so that it comes slightly over the earlier object. When doing this, you only need a few stitch points of overlap. As the stitch forms on top of the earlier column, the stitch will ride down and seat quite well, filling the gap.
Sometimes you have meeting columns that have low enough density that there will be something of the fabric visible. If you need to completely cover the fabric, insert a set of stitches as a separate object as a form of underlay. Usually you will do this with the same angle as the early column will stitch. This acts to bind the fabric down and provide the color needed when the columns intersect.