I generally use pretty fine edges so they get dull quicker but they seem to respond better to frequent stropping than coarser edges. On the occasion that I actually do compare edge retention, I'm basically talking about how fast a highly refined edge loses that feeling of ultimate sharpness which is generally pretty quick. If I was looking to see how long I could cut onions without smashing them, my impression would likely be totally different and the geometry of the blade/edge would start to take over. I'm wondering what everyone else is evaluating when determining edge retention.