I know this is an old thread, but times (and technology) are a-changin'! The modern files have a "twisted pattern" cut into the file which kind of does what I do by hand.... I also give the file a quarter turn twist when pushing it though (I think it helps with keepping the file level), but it's largely unnecassary with the new files. I just don't want to "unlearn" the twisty stroke now....
