After years of just assuming there would be differences between different steels, heat treatments, edge angles, etc, but doing little formal testing to confirm anything, I finally decided yesterday to do some proper testing on some of my knives. Specifically, this started because I have never had great experiences with Zero Tolerance knives, and I wanted to see if this was due to my bias against ZT as a company or if they really just do a poor job heat treating their steels. I borrowed a Spyderco Tenacious which had been gifted to my fiancee and sharpened it on the KME at 17 dps at a 600 grit "fine" finish, then stropped it on 0.1m diamond compound on leather. Next, I put the same exact edge on a ZT 0308. Both knives had a 1" section of mild belly taped off after sharpening. Then, I prepared a ton of U-Haul cardboard box panels for the test (with a third knife not being tested) to consistent and measured lengths. My testing would entail cutting the panels into strips along the grain and recording the number of times I cut a given length panel with the 1" section of each knife before 1) the knife stopped shaving hair, and 2) the knife stopped comfortably cutting held printer paper. I used some sheets of cardboard as my cutting board to prevent the knife from hitting the ground at the end of a cut. Standard stuff for edge retention testing, or so it seemed at the time. Here's what actually happened: The edges on both knives wore down at exactly the same rate, from what I could tell. Even though there's supposedly a massive difference between the knives, I could not reliably determine one knife to perform better than the other. I thought I must have screwed something up sharpening on my KME, so I very carefully sharpened the ZT up on a DMT fine plate, stropped it, and tried a second time, but saw no difference in performance. The point of stopping seemed completely arbitrary, and it was very difficult to tell when I should stop cutting and move on to the next test. For shaving, I could stop when it became difficult(?) to cut hair normally but I could always just increase the pressure and angle of attack and get the knife to continue to painfully scrape some hairs. This was especially difficult to determine with the paper cutting test, where a knife could be made to slice held printer paper slowly but consistently with the right technique, but was past the point where I would in normal use consider it dull. Unlike other testers I've seen, in no case did I get anywhere close to hundreds of feet of cardboard cut before a knife lost its hair shaving ability or even paper cutting ability. Both knives lost hair cutting ability after about 40' of cardboard. Knives started being frustrating to cut paper with at about 80', but could limp along making short but clean slices long after that point. I didn't go too much further with the paper cutting test as the edges would be pretty useless to me at that point. In a panic and wondering if I had messed up something in the tests, I grabbed some knives I was hoping would exhibit noticeably better edge retention and started cutting the cardboard. These included a Police 4 in K390 with 600 grit ~15 dps edge, a Benchmade 570 with a 600 grit ~15 dps edge, a PM2 in Maxamet (stock edge closely followed on DMT stones), and a Manix 2 in M390 (stock edge closely followed on DMT stones). The edges were drastically different, but this wasn't intended to be an apples to apples comparison; I was expecting to see a runaway in performance. These knives were razors when I started, but like the first knives none of them were noticeably better at holding a shaving edge after cutting a fairly small amount of cardboard. The Police 4 was doing a bit better with the paper cutting test, but after about 100' of cardboard it was past the point where I'd sharpen it normally. When in the realm of edge performance I actually care about, I saw no runaway in performance between the knives, not even with Maxamet. The biggest difference I could perceive between the knives was in ease of sharpening. The Tenacious got sharp easily and in next to no time at all, as expected of 8Cr13MoV, whereas the ZT took a lot more effort and required more care to get rid of the burr. Maxamet and K390 felt harder on the stones, but I liked how they feel when sharpening more than the stainless steels. The Manix 2 in M390 was easier and more pleasant to sharpen than the ZT, for whatever reason. On a light-hearted note, the testing made an absolute mess and my cat loved playing in the debris field I created. Our recycling bin is full, so I really should have timed this testing better. To be honest, I don't know what to think about what I saw during my tests. I'm sure every part of what I did could be disputed by someone, whether it be that my edges were not consistent, or that I had a burr on my knives that I didn't detect, or that I somehow cut the cardboard wrong or something, or that the cardboard wasn't homogeneous or consistent, but I did everything as consistently as I could, and I can sharpen a knife competently freehand or with my KME. I'm reasonably confident that nothing is particularly wrong with any of my knives. Maybe cutting U-Haul cardboard is just particularly hard on a knife? I don't know. If I need to devise ways to be even more controlled and methodical than this, and I need to run a ton of tests back to back and average the results to start to see definitive differences between steels, then I'm not sure any of the craze over steels with high edge retention is worth it to me. At the point where the super steels might have an advantage over lesser steels in working edge retention, in real life I would have written the knife off as dull sharpened it long beforehand. At least with corrosion resistance or ease of sharpening, the differences can be palpable even in an uncontrolled setting. I'm going to continue doing tests on my other knives to see if there's something I'm missing (in particular, retesting Maxamet and seeing if my 4V manix 2 is as good at holding an edge as it is difficult to reprofile). Has anyone ever tried doing something like this for yourself? I'd be curious to hear your thoughts.