If I end up with a seam allowance that is too small, I stitch a second (and some times third if the seam allowance is really worrisome) line of stitching along the seam allowance right next to but not on top of the original seam in a very tight stitch length. I find that if I try to rip a seam out that is too narrow, the the fabric in the seam can unravel and I end up with less fabric than what I started out with, and that amplifies the problem.
I wash all my quilts after finishing them in the harshest conditions I think it may encounter. If it's going to be used by a child, I use the hottest water and dryer temperatures. I look for loose seams or whatever problem that might show up so I can fix them. As I have become a better quilter over the years, I'm more confident that my quilts will survive harsh treatment in the hands of others.