Does Maureen Dowd regularly credit others for their work?

Yesterday, I noted that, according to Tucker Carlson, Maureen Dowd regularly uses other lines she hears from others, without giving credit for them.  That conflicted with a NYT spokesperson's claim that Dowd is "eager" to give such credit.  Here's Carlson:

[T]he whole thing is an interesting window into how her column is created. I knew someone once who was on her call rotation. Every week, she'd call and collect amusing lines from him, which she'd invariably use without attribution. Every writer does this to some extent -- I've made a lot of money over the years stealing from my conversations with Matt Labash -- but she seems to do it more than most.

Now here's Slate's Jack Shafer:

Right now, I suspect that, more than anything, Dowd wants the whole mess to disappear. Even though she has a reputation for routinely crediting others in her columns—a point Dan Kennedy makes today in his critical Guardian column—that doesn't really matter.

So, what gives?  Does Maureen Dowd regularly -- more often than other reporters -- use "amusing lines" without attribution?  Or is Carlson unfairly smearing her?

(Keep in mind that for Maureen Dowd, "amusing lines" aren't insignificant; they are her claim to fame.)