I think the bigger issue is that coding is about knowing what the hell you're doing. Copying a snippet manually forces you, as a side effect, to read the code,

I think the bigger issue is that coding is about knowing what the hell you're doing. Copying a snippet manually forces you, as a side effect, to read the code, and read it more slowly than you otherwise would. You notice the limits of your understanding more quickly, and can try to fill them in. I didn't learn with Zed's books, but I did (and do) avoid copying and pasting anything I didn't (don't) understand, and would recommend that approach to any newbie.