Don’t know about PyCharm, but in other JetBrains IDEs you command-click on a function name and it takes you to the declaration, and command-click on the declaration opens the list of invocations.
Not sure about bare PyCharm, but if I shift click on any function use, it goes to the function definition. When I shift click on the definition, it shows me all of the uses. I use a lot of custom shortcuts for things like refactoring (rename, move up / down the class hierarchy, move to another file, change signature / arguments) and to show quick documentation.
That should be CTRL+SHIFT+click, not just shift click. Muscle memory, heh.