I never knew that about needles - just kept on using the same one for years until it broke. Partly I did that because every time I would switch needles, I would lose some kind of bobbin or top thread tension and have to go back to the shop to get another reminder how to put the needle back in the machine.
That's the kind of thing that happens when you don't use your machine very much (I was only doing Christmas/birthday presents at the time). Now that I use it more frequently, I guess I'll have to get it together!