Accuracy. Accuracy in cutting the pieces of a quilt, accuracy in sewing a 1/4" seam, watching where seams come together and accuracy piecing the block after piecing the parts. Even being off 1/16 or 1/8 of an inch can have huge repercussions, as the error is repeated until you can have quilt blocks that no way represent the first blocks. That 1/4" seam plus the cutting are the two most important things we must do to create accurate piecing