Stitch-in-the-ditch is a technique where you stitch into the well of a seamline from the front of a garment to catch something behind; I use it most often to sew down a bodice lining to the waist seam of a dress or jumper to save the time it would take to sew it down by hand. Most instructions tell you to gently spread the sides of the seam apart as you stitch along the seam. Besides taking quite a bit of coordination to hold the fabric to the left and right while also allowing it to feed into the machine, I’ve come to think that stretching the fabric while stitching often creates an over-handled, worn look to the seam, or causes the seam to stay spread more open than normal, rather than lying as flat as it otherwise would. Instead, I’ve been satisfied with the results I get if I just make sure to press the seam nicely first, and then just stitch carefully into the seam. The stitching might be slightly more visible than if you spread the seam while you stitched, but it’s still usually hardly noticeable, and it’s quicker to do and gentler on the seam.