For me it happens when I am tired or not in the sewing mood but feel the need to push on and finish a step or project. Then I screw up royally.
Case in point.
Stupid screw up. My seam finishing for the 1940s blouse is french seams - even on the sleeves. On the second sleeve, it went in fast and easy with no puckers. So off I go with the big scary scissors to grade down the seam for the next step. Ugh, even though I was being careful ...slice...right through the sleeve. Then there was some yelling and agonizing that I knew I wasnt in the mood but felt the need to finish up the sleeve. Stupid stupid stupid.
I need to learn to read my own cues!! What stupid mistakes have you made that could have been prevented?
Myra - I love that little blouse too!! In fact, I have muslined it and cut out my fashion fabric but placed it on hold until I finished the 40's blouse. Maybe a post on that top tomorrow - it has been more challenging than you might think.
Amy - Oh you are a good person to want to give away vintage patterns. I tend horde the little lovelies so I can look at them and think about all the outfits I could make with them if I only had the time! Most of my vintage patterns are 50s and 60s with a spattering of 40's.