I don’t print any abrasive materials at all. Pretty much only normal PLA and PETG.

I noticed, that my print quality gradually went down quite a bit, especially in the last few prints. I had a lot of stringing, weird blobs, and scarred surfaces.

Now, the print quality is as good as it should be!

They are dirt cheap. You can get a set of 10-15 generic ones, in different sizes, for only a few bucks. Don’t forget that they are consumables.