Originally Posted by Cheri_J
you should change your needle after each project or every 10-14 hours of sewing. That's what my dealer told me.
That is the standard answer. I never think about it until after I have started a project, all threaded up and am already sewing. So, I guess the answer to your question from me is every couple of projects (not often enough). Also I can "hear" the difference when the needle is not sharp - it does not pierce the fabric and glide through smoothly but "makes a noise" when it hits the fabric.