Everybody has different techniques. For almost all longrifle carving, I don't use any kind of a riffler file or rasp. It could be beneficial I suppose, but I don't feel it can make up for good carving technique with edged tools. I've noticed some tend to rely on them to create smooth and level backgrounds. It often doesn't work well in my view. With that said, in the right hands, I know they can work. Acer has shown how he uses a little rasp he made for working carving background and he ends up with very nice results. I'm sure he could end up with good results just using an edge tool as well. So, maybe they can help, but I don't think they will make up for lack of skills in other areas.