On my sewing machine, I'm like MICHELLEOC in that I have several projects going on at the same time and sew for different lengths of time....sometimes all day = sometimes for a few hours in the evening.
If it's a customer's item I'm working on, I put in a new needle automatically. I may continue to sew on my own projects while using this same needle. Then if there's a quality issue or if the stitching 'pops', I change the needle again and the problem is solved. So overall the needle is changed quite frequently.
On the longarm machine, however, a new needle is put in with each quilt.
Nan - IN