If the undo process was very long and frustrating I know that I have to give it a rest before I redo because if I don't chances are pretty good that I'll make another mistake very soon down the road. I'm much more likely to mess up if I'm tired or distracted. The most frustrating thing for me is to sense a hint (Is that fabric upside down? Do I hear a funny sound from the machine? Is the tension still set for the last project?) and yet find myself just continuing to the end of the seam or whatever. Disregarding even the least little bit of an anomaly is almost always going to result in just that much more un-stitching, but I seem to have an almost irresistible urge to fight that gut instinct that tells me something is wrong and I need to stop - NOW! - and find out what it is before it gets worse. There's a little lying devil on my shoulder saying, "Shut up! It's fine!"