Reply by MisterInquisitive

Yes, doesn’t have to be perfect, just get most of the junk out. Another thing comes to mind: never draw a file backwards through the (metal) work. It damages the teeth. Just forward on a cut stroke, and use a light touch—just enough for it to cut. A light touch allows the swarf or sawdust to clear the teeth so the gullets don’t become prematurely galled up and become ineffective. Files are considered expendables, like sandpaper, but they can be a bit pricey, and with a little care can be made to work well for a long time.