If you invest in a couple of diamond stones, your filing will become necessary only during special circumstances. After you shape your geometry, a few diamond swipes a day go a long way. I determine if my edges are sharp by how much of my fingernail they can scrape off. A nice white shaving falling from my fingernail is my preferred edge.
Buy 2 or 3 diamond stones of different grits. Starting with corse- swipe them just a few times until the sound of scraping goes away. Then switch stones to a finer grit and repeat.
However, in the past I had spent entire seasons filing with files almost 3 or 4 times a week, lightly, and never wore out an edge. back then, I didn't realize how much diamond stones actually cut, and now they are my routine in place of filing.
also, if you hit any little pebbles or rocks, those burrs on your edges are heat tempered. Meaning that they will damage your file. Swipe with a corse diamond before filing to break that hardened metal. (assuming you actually need to file.)
If you don't want to spend any money on diamonds right now, relax. Clean and easy swipes with your file will not highly deteriorate your edges, and filings are very common.