I very rarely fix my mistakes on family quilts. That means you can definitely tell the progression of my quilts. The first ones don't have enough quilting & have a couple wrinkles even in the top. As I went on, they improved. My current quilt has some seams that switch directions partway down. On top of that, I decided to applique the letter "K" (for Kahlan) onto a few of the blocks as a Hidden Puzzle because one of the pieces of my Irish Chain had a small tear in it. Turned out to be needed for a few other blocks because the repro fabric didn't always survive the pin basting. It's frustrating, but the quilt is for a 3 year old. I'm not about to spend another 100 hours to make it show-worthy. After it's been through the dryer a few times, no one will notice but me (my home is a Quilt-Police-Free-Zone). And she loves looking for the K's (they are the same color as the background square so they kinda blend in).
For client quilts, if it's something I think will bug them, I'll pull it out. If it's some tiny thing that only I'll ever notice, I leave it in.
For show quilts, nothing less than my very best is sufficient. Uneven stitches? Pull it out. Seams don't nest perfectly? Re-do it. It means it may take me 4-5x longer, but what else can I do? All those tiny things will be noticed by the quilt judges.