This was a shortcut I knew. But did not find a practical use for it. Till recently when I was conducting a session for the legal team of an insurance company. If you work on large and complex documents, I am sure you will find this useful.
You are editing a complex and long document. While scrolling or navigating, something goes wrong and you suddenly land up in a completely different, far away place in the document. You did not know where you were, nor do you know where you are. You just want to go back to the original place where you were editing. Bookmarking is not an option because you could be editing anywhere, you cannot keep adding bookmarks all over the place.
The solution is simpler than you think. Just press SHIFT F5. Word remembers last THREE editing positions. That solves the problem elegantly.
Also appreciate someone who thought of this need and provided a solution 20 years back!