I've done that! I made a quilt for my niece while I was very sick and made a TON of measuring mistakes and so when I assembled it I had to make some strategic tucks and pleats to make it all work - I didn't have time or fabric (or energy) to start over. I went back over all the problem areas with decorative stitches (and then more elsewhere so it looked balanced and planned) and nobody ever guessed what was hiding underneath all those stitches!