Twice. Wrong. I suspect ultracrepidarianism. Most crowning files are as good as trash in my book. With most of them, either you abandon quality work altogether, or you take waaaaay too long to finish a proper job. Premium triangular files in the good hands with the proper savoir-faire do a hell of a good job, but it took way too much time to my taste. I've tried everything on earth and settled on the original Z-file from Stewmac. Not to say that it's the best, just that it suits my hands, moves and logic better than anything else (as of now) and that it improved my work dramatically once I got the hang of it (which is not as obvious as generally considered, actually).