Quilting is about piecing. I piece whatever I need to. If the material has a very definitive pattern, I try to match the pattern up so that the piecing isn't obvious. If there is no pattern, then I just piece it and go. Once the quilting has been done, you won't even notice it.
All that being said, I don't piece within a couple of inches of the length of the sashing (or border). I try to add at least 6 inches or more. You will have at least 10 inches, so it should not be noticeable once you have the quilting done.