As someone who has taught college level writing for more than 20 years, I can tell you that too many people learned this tip way back when, and the result is commas every which place with no rhyme or reason to them.

People need to learn the particular sentence structures that require commas — such as restrictive (or bound) and non-restrictive (free) modifiers. It’s harder than following some “easy” tip like Danziger’s, but much more accurate.

What I do now is have students copy all the sentences with comma errors I mark in their work and paste them into a file, then I tell them to look for patterns (and any repeated pattern in their next writing will be marked down significantly). More often than not, their errors fall into a particular pattern (such as failing to put in the second comma after a non-restrictive modifier), or separating their subjects from their verbs with commas, or failing to put a necessary comma after however, or putting an unnecessary comma after but. The problem is that people don’t always inflect various sentence structures the same way as they read. While they don’t necessarily need to know the names of the structures, they do need to be able to recognize the patterns.

Danziger’s big tip for using the semicolon can also lead people astray. Danziger says: “When you use the semi-colon within a sentence, you should be able to replace the semi-colon with a period. The words on the left and the right sides of the semi-colon must be able to meaningfully stand alone without any further revision.” While that is true for semicolons used to separate independent clauses (absent a conjunction), it is definitely NOT true for semicolons that she notes on the same page:

“2) It separates items on a list, especially when the items on the list contain commas.

We visited the following cities: Paris, France; London, England; Rome, Italy; and Geneva, Switzerland.”

Following Danziger’s tip, you should be able to insert periods above between France and London, England and Rome, Italy and and. Obviously you can’t or you end up with sentence fragments. So if the only thing people remember from Danziger’s discussion of semicolons is her tip, they are bound to make mistakes on the occasions where semicolons are needed with items in a series. And there’s another problem: many people cannot recognize sentence fragments.

Sometimes I think it would be easier to teach writing to college students if I could erase everything their elementary and high school teachers taught them!