Graham, could you please explain this: "opening documents, modifying them and saving them as something else. This is a recipe for disaster." I'm sure I've done this a thousand times if I want to reuse most of a document. I might open a document used for a July newsletter, change it for September, and save it under a new name. Is it important to save it under a new name first and then modify it?

Graham is spot on. Save as a template and then use that template for new documents. A template is not "opened" in normal use; it becomes the format for a new document.

If you've done this thousands of time and this is the first time it has caused problems you have been extremely lucky.
Templates in Microsoft Word
The kind of template we are discussing here is a "document template."

I'm not the original poster.

Let me expand my example: a simple Word document with text that remains mostly the same from one use to another would be the company's blood drive announcement. The location, times, and contact person are always the same. Only the date changes. I normally open the docx file and change the date and save it with a new file name, maybe blood-driveSep.docx instead of blood-driveJul.docx. Is this not "opening documents, modifying them and saving them as something else"?

If you say it's dangerous, I won't do it, but I was hoping that someone might say why it's bad. The document is based on the Normal template, and the content is eventually copied into InDesign, so I don't follow why it needs a template of its own. To avoid disaster, I will try to remember to Save As first and then change the date. That's OK, isn't it?