I was so so proud of my lovely, little, straight stitches on the side of the bodice… then I realised I had forgotten to put the ties that will form the bows in the seams. So I though “bah, I’ll attach them in another way, the stitches are so pretty, I’m not undoing them. And they’re so small, I’m no unpicking them in a hurry!”
Then I looked at the instructions and realised I’d done it wrong anyway – this bit was meant to be based after I’d attached another bit properly and was only to be sewn properly later…
The unpicking took a long time.