Ideally, no matter what sharpener, the more consistant you are in following the mfgrs angle on the edge, the better life is, lol. I'm a knife sharpener junky, bought every new and better, blah, blah, blah. The one I'm most fond of is called a Jewel Stik, sold by Cabela's and is the three sided version. It has diamonds embedded in the surfaces, and it doesn't matter what angle you hold the blade at, as long as you hold the same consistently. the coarse one will quickly put your own personal angle on the edge, the medium smoothes it out, and the fine turns it shaving like a razor sharp, as long as you hold the same angle for every stroke. Not as hard as it may sound, as when you have the correct angle, it will feel like you're slicing a sliver off of the sharpener.