Kitty Litter. Week 10

Week 10 is over: ~31% of the picture, 172 hours of work.

I've got a theoretical question: how long does a stitching needle usually last and how to identify a good embroidery needle? I started this picture with a "kit needle" and after a few weeks noticed some usage marks on it. I didn't expect much of it, those "kit items" are rarely of very high quality, but this one had a really short lifecycle. The needle became darker and darker and more difficult to work with, so after ~120 hours I decided I deserve something better and changed to some Prym needle. Now after 50 hours I still see no signs of wearing out on it (and I was using the same needle for some Hardanger embroidery before).