There actually is a file especially made for filing points, but it is an all but forgotten art.
As the points are making and breaking contact, they are turning the coil on and off at specific intervals. When the points open, the coil primary side ( the wire that goes from the distributor to the coil ) gets a big shot of instantaneous voltage generated by the energized coil - like, maybe, 500 volts, or so, for just an instant. That much voltage causes an arc across the points. To keep the points from arcing and burning from that much voltage, a capacitor is used to “charge” and absorb some of the voltage, putting the points at zero voltage when opening and closing - THAT is what a condenser does.
Usually, a condenser either works or it doesn’t and while they can break down over time, one minute the engine is running and next minute it’s stopped because of condenser failure. If the condenser fails, usually the points are fried by being either welded together or burned so badly they can’t make contact anymore. When that happens, pop in a new set of points and a new condenser, adjust the point gap at wide open (the thickness of a common matchbook usually works pretty well in a pinch) and you’re good to go.
Now, about filing them. First you have to know if they are good enough to file, ie; are they pitted so much that filing won’t help, like having a big peak on one side and a crater on the other (a sure sign of a failing condenser).
Next, you need to file them perfectly parallel, which is best done in a vice, although I have had OK luck by doing them in my hand on the side of the road.
Lastly, filed points are just a stop-gap and don’t last nearly as long as new points. The old points failed because the condenser was not exactly the correct capacitance value for your coil or had changed capacitance value over time as it weakened - they make a tuned circuit together and when they’re not in tune it causes point pitting (burning). Installing BOTH points and condenser at the same time will work fine 90% of the time. Good ( read that, OLD ) mechanics can tell if you have the right condenser value for your coil just by looking at the points, but us “Auld Pharts” are a dieing breed, these days. Just pop in both points and condenser, adjust the point gap as your service manual or the Bob and Dave VW page instructs you ( it’s not as hard as it sounds ) and you should be fine. The old adage was new points/condenser every 12-24,000 miles, depending on car, but I’ve seen them last for 50,000 miles, too, if they are both perfect for each other.