For example:
I had a Service Manager coming to me and asking a simple demand like: I want a list over all my groups that I mange and its members. It sounded like a easy thing but all I knew was that I could go the the "groups" list and then I hit the wall trying to figure out how to filter/config layout to give me the result I wanted.
And after searching quite some time since I didn't believe I was the only one with this problem I found the solution. There are a few tables that combines other tables by default. You just need to know them.