Folks who use the Chicago Manual of Style frequently may know that the editors publish an online Q&A series monthly; you can sign up to receive Q&A alerts here.
The best thing about the Q&A series is not the answers it provides, but rather the voice in which it’s written. Sometimes, the writers admonish:

Q.  I recently mailed a flyer to my tour group and used the phrase “The Pavilion houses the museum’s collection of Japanese works dating from around 3000 b.c. to the twentieth century,” which I had copied from the Los Angeles County Museum of Art web page. After I clicked the Send button I realized the b.c. was in lowercase. Should I email a correction to the museum staff?
A.  A correction—or an apology? I checked out the page you refer to, and on my monitor the abbreviation appears correctly in small caps (B.C.), which can get lost during the transfer of copy from one electronic platform to another (such as copying and e-mailing). If you put quotation marks around the phrase and credited the museum’s site, your only crime was a failure to proofread. If you simply pasted without attribution, that’s plagiarism.

Other times, they tease:

Q.  I read a lot and have been working on a novel of my own for a while now. In most of the materials I read the authors use “had had” and “that that” quite often. For example: “He had had the dog for twelve years and everyone knew that that was the real reason he didn’t want Animal Control to take it.” I doubt there is any actual rule against this, but I find it to be unattractive on a purely aesthetic basis and try to avoid it like the plague when writing. Is there anything to this or am I just weird?
A.  As you can see here, correct isn’t always pretty. So you aren’t weird; you’re a writer, and one of the things that makes you a writer is that you’re sensitive to ugliness. Once you’re sensitive to clichés, you’ll be all set.

Other times, they provide an important clarification:

Q.  In a bibliography where the title of an unsigned article is a date (“1939: The Beginning of the End”), does the bibliography begin with this entry, or is it alphabetized according to its spelled-out word?
A.  It’s usual to file a title like that under the spelled-out version of the number, in this case, nineteen. However, in lists where many such titles begin with numbers, you might rather group them all in numerical order at the beginning. In rare instances you could post an important title at both locations or add a cross-reference directing the reader to the location of the full citation.

In this case, for example, I think it’s extremely important to note the authors’ recommendation that a critical title be included in various places a reader might look (i.e., under “1939” and “Nineteen thirty-nine”). This recommendation shows a sensitivity to readers’ needs that one might not necessarily expect from someone who literally wrote the book (and the rules) on editorial style.
That’s another thing that makes this series so interesting: the authors’ ongoing theme of not just following rules, but of thinking about the ultimate purpose of rules, which is to remove barriers to understanding a piece of writing.
When you know the rules of style and can judge when to bend or break them, you’re on to something good.