I've a small red slip stone that I take for the golok in case I hit something I shouldn't. Thing is I've only had to use that a couple of times, usually field maintenance is done with a couple of different bits of wet-n-dry paper. I think files are the absolute bowels when it comes to maintaining an edge. I completely agree with Mike Stewart of Bark River in this regard. Files may be quicker at sticking an edge back on but they also guarantee they you'll have to do it more often. Some people seem to like the lock-in of that and constantly file at their machetes to keep them sharp. Despite giving a good amount of relief to mine behind the cutting edge the very edge itself isn't anything like as acute and is a fine finish convex I have to do something pretty dippy with it before I need to take a hard stone / diamond to it to fix it up. And that's with a #2 which isn't very hard really, more tough.
Never used anything more than paper to fix a hatchet, although I take the same tools for that as I do the #2 just in case.