I do something similar, but instead of 8 groups of 2 I have 4 groups of 4: 00xx 01xx 10xx and 11xx. I also have some freebie groups that I just know, like 0001

I do something similar, but instead of 8 groups of 2 I have 4 groups of 4: 00xx 01xx 10xx and 11xx. I also have some freebie groups that I just know, like 0001 0011 0111 1111, the powers of two, 5 and 6 from working with chmod, etc. A B D E still give me trouble, but that's what a tool like this hex quiz is good for!