Pad stitching is easy peasy to do once you get the hang of it, and you easily get into a 'rhythm' which makes it much easier still. You just have to remember a couple of things.
Keep the collar folded (pref. over your finger) at the fold line
Keep the stitches small
Keep the stitches as even as possible
Each line starts at the opposite end to the last - this is what causes the chevron shape.
Pad stitching not only shapes your collar, but it also ensures that the collar lies flat and where it is supposed to be.
Here we have one side padstitched, and the other not. You can clearly see how the pad stitching has helped the left side lie flat while the right side is distorted out of shape because it is bouncing back upwards.
Now complete, my collars are beautifully shaped as the pattern intended and nice and flat too.