The Origins Of User Interface Patterns

Have you ever asked questions like "Where can I use icons in my application? Where shall I place the header and detail data? Should I provide collapsible screen areas? How will users search? What about inserting new lines in a table? How to...?" while developing the user interface of your application?
If you have asked such questions (and we know you have!), you know how difficult it is to find good answers. And even if you have found some good solutions for your domain, your colleague, working next door, may have found other, or even better, ones. So, starting with a handful of questions, each leading to a couple of design alternatives, you easily come up with a large number of different user interface variants. Which out of this huge amount of alternatives is the best one; which one is the agreed upon user interface (UI) for your department?