Those threads don't seem to be delinting themselves and messing up the spring tension as much as the others, but I also clean my machines more often than is strictly needed.
The quilt batting on the other hand, holy COW the mess that makes in the hook area.
Because of the mess I keep finding, I've taken to disassembling all bobbin cases and cleaning under the springs. I just turn the screw in until it stops, make note of the number of turns, then remove both screws and clean like crazy. Then I reassemble to the same spec and test from there. More often than not, the case doesn't need any more adjustment, and the tension problems magically disappear.
One of the bobbin cases was so packed up that there was a "chunk" of lint under the spring that I had to "chip" off with a small blade screwdriver. DH caught me muttering "THERE's your problem...."
Another one was so full of lint in the hook area, I took an air compressor to it.... there was fluff floating all over my sewing room (in my eye lashes, my hair, all over my clothes...) for a good 15 mins at least.
I bought a little Genie for parts this weekend. I hate to do it, but I needed the pedal, and the machine was missing the slide plate and the hand wheel was cracked in 2 pieces. It was surprisingly clean in the hook area, but maybe that's the lack of a slide plate. The lint could escape.