That's true but I did say "nearly every letter" not "every letter can be". The point was that 7 is a very good estimate for the number of bits needed to define

That's true but I did say "nearly every letter" not "every letter can be". The point was that 7 is a very good estimate for the number of bits needed to define the shape of a letter. We could add in a few "edge case segments" to get the rest of the way, then look at how frequently those segments are used, calculate the entropy change from Shannon's formula and refine our estimate. But that's a lot of work for something that isn't going to move the needle very far from 7.