I only sew in one direction myself. If i make sure i'm not pulling or stretching either of the strips, there is no problem with accuracy for me. I stripped pieced an irish chain quilt for my parents 50th, and they were very small 1" strips, and because they were such thin strips, wonking would have been very easy, but i just made sure it didnt happen. An ordinary bed quilt, wonking doesnt show so much, but on a wall hanging, any inaccuracy with make the quilt look very wonky while hanging. So this is just in regards to the remark, prove it to me lol lol, but, this is not to say that now that i've heard of this technique, that i may choose to use it, if i ever am going wonky, but i just don't allow wonky's to happen lol ... when i did have it happen once, was very mad, and figured out why it happened, that i had been pulling too tight on the top strip while sewing, and well, that strip got a yelling at and disappeared lol, but never again