Keep nail files around
Just file once a week. Depending on genes, nails may break easily. Nails often break if they are uneven, and nails naturally grow unevenly. So stash files everywhere, and whenever you see unevenness, file them all to the same length, shape, and size. Make sure to file in the same direction, to prevent nail breakage. Replace your file every month, or even before the grain smooths out.