I am only a home cook, but over the past few months I have watched quite a few knife skills videos on youtube because I wanted to improve my knife handling technique. One thing I noticed over and over again when I watched people cutting onions is that they do not only do the lengthwise cuts before the final crosswise "dicing" cuts, but also cut up the onion horizontally with two or three cuts, either before or after the lengthwise cuts.
Does this really help/improve the final result or is it just some thing that is handed down from one generation of cooks to the next without really questioning the effectiveness? If you consider the internal structure of the onion it is hard to see how it can accomplish anything positive. Actually, it wrecks the internal structure of the onion and makes it hold together less well when you do the fnal dicing cuts. You can even see the onion literally fall apart during the cutting process, and not in the good way.