If you’re filing something (like a piece of hardware, as seen here) and it seems to be taking longer than expected, shift farther down the file.
Take short strokes as close to the handle as you can work. If it cuts better and faster, the file is worn out and should be replaced.
Seems obvious, doesn’t it? So why did I just waste ten minutes, when I should have checked last time I used it? Looks like I’m off to the store.
How (mildly) annoying.