How it works…

I've seen people who use PostgreSQL with thousands of databases, but it is my opinion that the majority of people use only one database, such as postgres (or at least, only a few databases). I've also seen people with a great many schemas.

One thing you will find is that almost all admin GUI tools become significantly less useful if there are hundreds or thousands of items to display. In most cases, administration tools use a tree view, which doesn't cope gracefully with a large number of items.