I never trace patterns and once I've determined the size I need to cut I always cut the pattern. Mostly I sew for myself and know what's right.
But I decided to make DH a shirt. I measured one that he wears very carefully and decided to cut the pattern to the medium size. At the first try on it wasn't as roomy as I had anticipated. By the second try on I swear that it was shrinking. I finished it this morning apart from buttons and buttonholes and comparing it with his shirt nearly 4" seems to have vanished.
Fortunately it was only intended as a wearable toile.
So I had to root around in the kitchen bin to retrieve the bits of tissue I'd cut off the pattern and have spent a tedious hour with glue stick and tissue adding the cut off bits back on to the pattern pieces.
Once I've got the pattern right I will recut the pieces in new tissue or perhaps I should leave them as they are so that the adhering bits of black bean sauce forever remind me of my folly.