I'm not sure you understand what "uses Pinterest" means.

Brides typically use it to decide what they should wear, what their wedding party should wear, and what decor should be used at their reception etc. See for example [1],[2]. Note that [2] has 4 million followers, for that board alone.

If it's studies you want, then something like [3] shows just how much traffic Pinterest drives: much, much more than Twitter, and second only to Facebook in terms of social sources.

It's not typically used as an organization tool in itself.

[1] https://www.pinterest.com/categories/weddings/

[2] https://www.pinterest.com/explore/wedding-ideas/

[3] http://www.businessnewsdaily.com/7356-social-media-marketing...

I'm referring to brides using Pinterest as a planning tool (before the wedding).

I can't believe you just asked me for a study based on that comment (where "every" is clearly hyperbole). Let me Google it for you (EVERYone uses Google).

Look at that ... 70% of women use it for wedding planning BEFORE EVEN GETTING ENGAGED

http://www.huffingtonpost.com/2014/07/25/wedding-survey_n_56...

You attended the weddings as a guest? Brides and grooms and wedding planners and venues make extensive use of Pinterest. Pinterest is brilliant for that kind of thing. You probably don't see that as a guest.

Sure am tired of seeing that comment everywhere!