You might want to watch Patrick Lose demo he did on F&P, He stitches up to 1/4", then he sews off to the corner and cut the thread. Make your folded corner and continue sewing and repeat this process three more times. Then you can open the seam and clip the dog ears that is just extra fabric and your corners will fold more neatly. I saw him on the F&P TV show on PBS. Not sure if there is a U tube video. I have been quilting over 30 years and this, once you got it, helps to get that perfect miter corner and get rid of some of the excess bulk. I sewed 1.75" double folded binding on my Mug Rug, sewing it to the front and hand stitching to the back.