One of the most common complaints about home sewn pillows is that the corners protrude or stick out beyond what is eye appealing. There are solutions to those corners sticking out or protruding. The first step is to sew a cover that is the right size for a pillow form.
The free pattern for a removable basic pillow form cover is a classic example. Although the directions call for a half inch seam allowance, the cover is cut to the size of the form. This allows the entire cover to be filled by the pillow form. If the finished pillow is the same size as the pillow form, there is not enough pillow form to fill all the way out to the corners.