The October 17, 2019 New York Times featured an article about the impeachment inquiry: A Blockade Crumbles as Witnesses Agree to Talk. Here’s a sentence from the front page:
One by one a parade of Trump administration career diplomats and senior officials has offered a cascade of revelations.
The article was a long one that continued on an inside page. Here’s what I found there. Notice anything?
We have a problem. The sentence on the front page uses a longstanding subject-verb agreement rule: “a parade…has offered.” You skip the “of” phrase when you choose your verb. (You can learn more about this rule by clicking here.)
One by one a parade
of Trump administration career diplomats and senior officials has offered a cascade of revelations.
But the person who wrote the box ignored that rule (something that even good writers are beginning to do). Here’s what I mean. They skipped “a parade” and made the sentence about diplomats and officials:
A parade of career diplomats and senior officials speak up.
Because I’m a diehard, I’ll probably continue to use the traditional rule: I like its precision. But nowadays you’re free to ignore it.
Note, however, that if you’re a professional writer, you have to heed the guidelines of the organization that’s paying you. No company is going to flip back and forth between two versions of a rule. (Well, the Times just did. But you know what I mean.)
In other words, look at the style guide you’ve been given. How do they do it? Go thou and do likewise.
And if there isn’t any style guide, you need to be consistent. Use the rule or skip it: you have my blessing either way. But don’t jump back and forth!