Having Used PRO now for about a year, I've warmed up to the way Projects, maps and Layouts are all organized but during that time my projects have evolved into a rather complex net of data connections.
In a perfect GIS-world we'd have very tight data with maps and Layout pathed to specific sources. In reality, I have SOME data that is universal across different maps/layouts but I also have MANY "exceptions". Various "soft data edits" and one-time shapefiles that management wanted to see on a map for a given presentation. Another explanation are "what-if" scenarios. Maps and layouts displaying data that you need to show - but probably won't be updated for a long period of time. (But you need to keep in a particular map/layout in case management wants to chase that idea in the future).
What I'd like, is a feature in PRO where I can analyze an entire project and this analysis gives me a report/spreadsheet/other-output, that shows me what data is in the: Project>Map/Layout and the paths to that data. Ideally this report or output would give me a color code to indicate if certain data is linked/joined/or has a relationship class associated with it along with what it's linked to. In addition to a report, a "map" or diagram might also be helpful where we could see the connections between our maps and the data that make them up. (I'm envisioning a diagram/map similar the maps that show airline flight paths and their connected cities. In our case, the "cities" would be data sources, our map would be in the middle, and the paths would literally be the paths to the data in that map. Joined data could be indicated using a line in a different color. Arrows could show data relations). A separate report/diagram would be required for each map/layout.
I realize this is an entirely new feature, (and perhaps quite involved??), but I think many users and especially data administrators and GIS Mangers would find it extremely helpful. Most GIS users and authors find visual data and visual representations of data very easy to work with since that's our "bread and butter" day to day work. (Think of the popularity of Model Builder and even FME in the GIS world. There are many of us that think about our data visually). I'm a one-guy GIS shop so I have a good idea of how all of my data integrates with my maps and layouts but in an organization with many users/editors/ and administrators a tool like this could be VERY useful. Perhaps this might even be an add-on or extension? This is something I would use several times a week.
If solutions like this already exist I'd be interested in hearing about them.