I’ve described “pull quotes” also known as “break-out quotes.”
What I didn’t say was that it is effective to include a break-out quote on all or nearly all pages of every marketing piece.

Every page of a brochure.
Every page of a website.
In ads.
On postcards and other direct mail pieces.
On trade show displays.

Can you overdo it? Possibly. In most cases I don’t think I’d include more than one per page or side.
They are one of the best things you can do to build interest and credibility.
Ideally, as with other situations in using testimonials, you show the full name of the person, their job title, company name or location, and even a thumbnail picture of them. You can’t always get an okay to do all that, so you do the best you can do.