Just because a needle isn't broken don't assume it is useable!

Needles need to be changed to match the type of work you are doing. In relation to the cost of the fabric and threads you are using the needle is relatively negligible in the cost but can ruin the work if burred or bent.

We recommend changing a needle every 6-8 hours of stitching, certainly at the start of a new project. A needle works hard penetrating the fibres at speed pulling the the thread in and out for miles.
Learn to listen to your machine you will hear a pop as the needle blunts.

If in doubt change the needle!