I copy/pasted the code examples, reformatted them so they'd work in a different language (javascript), and refactored it to write my own language instead of Lox.

Then I did it again with a different destination language design, and had to reference the book less.

Whenever I end up writing an interpreter for a third time, I'll probably be able to do it without referencing Crafting Interpreters at all, if I had to. But I expect I'll still check the book before doing certain fiddly parts of the parser.