Pattern placement of formal drapery valance
This formal treatment strongly emphasizes the center, so the feature motif within the pattern repeat should be centered from side to side. A closer look shows that the pattern is also carefully placed in the vertical space as well. Vertically, it isn't "centered" it is in harmony with the scallop or the scallop is planned to enhance the natural flow of the fabric repetition.
When jabots are cut, it is not always possible to make them match. The height can match, and some portion may be able to match, but rarely is the left edge of the fabric the same as the right. Most often the pattern begins on the left and is repeated once or a few times ending with the right edge of the motif on the right.
The placement of the fabric within each drapery becomes more critical when there are architectural elements that can provide easy reference points to visually measure pattern placement.
Pattern matching to create identical treatments is essential for most styles when they are in the same room. Often, the usage of fabric is less than efficient. You may want to ask if the scraps are large enough to make pillows or other decorative items.