In most cases, the boning is aligned to the seams of a corset, but when using spring steel flats this is not always an option. Spiral steels can curve and twist with a boning channel, but spring steel only flexes in and out, so it must be vertical to the curves of the corset at all times. When the seams of the corset do not lay on the vertical, it can be difficult to determine exactly where the boning channels should be.
This demo shows one trick you can use to find the vertical placement of boning on a corset, regardless of piecing.
Boning Channel Alignment Trick