Farther and further provides a great example. Farther refers to distance. Further refers to all other cases, especially extent or degree.
Consider the example sentence in the graphic above. Confusion on the writer’s part is understandable in this instance. After all, corrosion could be measured in terms of the length of missing material. However, the writer of this sentence appears to use corrosion in terms of extent. Thus, the sentence should be revised as follows:
I have encoded that distinction into a mnemonic device that helps me to remember which word is most appropriate. Go further with all but distance. Feel free to use it if it helps you. Or find something else that works for you. Whatever that something is, using the proper word will improve your writing. And better writing better represents both you and the brands associated with you.