I actually don't agree with Rocky on the need to center every color boundary. But, if you choose not to center a color boundary, you should hold it straight parallel to the edge of a pleat so that it looks good geometrically, rather than tapering both sides of the pleat.

What *is* crucial is making sure that pleats are mirror images of each other across a pivot (and your example doesn't do that). And you absolutely need to center any pivot.

I agree with Rocky that it's rare to be able to exactly match a tartan in the pleats. You come as close as you can, but some color bands will be wider than in the tartan and some narrower.