I tend to put in a new needle when I start a new quilt. I say tend because I sometimes forget. My Bernina has a display when it is time to oil her or bring her in for a maintainence. So far I have only had to oil her and I have a back-up for when she needs to go to the shop. Since I CAN'T be without my machine, I try to clean out the lint after a big sewing job, check the thread route for lint and change the needle if needed.