I don't do this systematically, but sometimes there's something in the material that spontaneously causes me to come up with such a mental image.

An example from some time back, when I was studying for what I think was either a Data Communications or Operating Systems course:

In the dispatcher/worker model for e.g. a web server, there's a single dispatcher thread doing an infinite loop, waiting for incoming requests and then handing them off to worker threads that sleep until awakened by the dispatcher's task.

This brings to my mind a vast underground library with an undead lich standing in the front hall. At his feet is a vast pile of bones. When living visitors come in and ask to see a book, the lich uses his magic to animate a fresh skeleton from the pile of bones. The skeleton goes to get the book for the visitors and then falls back apart at the lich's feet. Any visitors to the library must wait for the skeletons to bring the books to them: for whatever reason, they are forbidden from fetching the books themselves.