After reading this post, I have started to organize my documents and projects according to the description. I feel like this is going to be helpful not only so that I can find what I'm looking for, but so that I don't have 4 copies of every giant source code repo taking up my disk space.
I do have one question: in the examples, the category shows "40-49 BlahBlah", but the subcategory goes "41 Taxes, 42 Expenses, etc." Is there a reason why X0 is skipped? Is this so you have room for something you might have forgotten?