most often I take it out.by insuring both sides meet up at 1/4" I can insure a perfect seam. I am the first one to admit that my seams are often off . My problem is making them to narrow so w hen they are narrow I will leave the thread in place and sew over to make the seams the right side. Either way getting that perfect 1/4" is the challenge. My seam ripper is always at my side.