Imagining how I might use a gradND, it might be a landscape with a bright sky to be tamed, with maybe some darker vegetation lower down. Reasonably careful alignment of the scene and filter would be good, and I expect the camera would be supported by a tripod for this. One might turn the grad filter to match the angle of the horizon, adjust the camera so the horizon passes through the middle of the frame, and click away. Can't shift a screw-in filter up and down anyway, I suppose.
There was a good illustrated short article in Pop Photo a few years back that impressed me. The example landscape's foreground was sunlit desert and there were shadowed cliffs in the background. Bright blue sky too. So how to deal with the wild contrast? They shot two exposures of the scene, one for cliff shadow detail, and one for the sunlit parts. Scanned the negs and combined the appropriate parts of each exposure in Photoshop. A grad filter couldn't have done it, as the different areas were quite irregular in shape, but these could be separated/masked in software. Now THIS method would work fine with an RF camera!