Do you think the default Revit view structure in project browser is messy? Below is from the sample file, and only have 3 levels. You can imagine how difficult to find views if you work on high rise building. Especially if you create many views to help you during the design process (read this working vs. sheet views by Kate Morrical).
We would want the project browser to be more organized. See below, the views are organized in categories and sub categories. Looks neat, isn’t it?
If you want to see how you can manage your browser like that, go read David Light’s post here: Get your views in order – Project Browser.