I have trouble at the end of the line of stitching, so I use the point of a bamboo skewer to guide my stitching of the last inch of each set as I chain piece.
I figured out that the prongs of my 1/4" foot make a little bubble of fabric between them as the last inch or so of each pair of patches passes over the feed dogs. The skewer really helps keep that last bit flat and my stitching line straight.