Sorry but I have to disagree with changing the needle, with every project. I only change my needle when it stops working smoothly and quietly. That amount of 'mileage' varies, depending upon what's being sewn. A good quality needle will last through many projects, before it needs replacing. Needless to say, I don't sew over pins or use a fine needle for heavy fabric.
I've been sewing for over 50 years and have an old Kenmore, an inexpensive Brother, and a 'fancy' Janome machine. The only time I frequently changed needles was when I was young and in the habit of sewing over/onto pins. Also had a bad habit of forgetting to change to a large needle, when sewing denim. Lots of needle changing, back then . . . but it was usually because the needle was broken or bent.
There was an occasional dull needle but back then, few lasted long enough to get dull.
