For every new document the generic name "Untitled 1" is suggested by Writer. That creates a problem if a file named "Untitled 1" has already been created in that folder. In that case the suggested name has to be changed manually by the user.

I would suggest to change the proposed name automatically from "Untitled 1" to "Untitled 2" if "Untitled 1" is already given (numeration should be continuously increased if document is already given).

An even better enhancement is https://bugs.documentfoundation.org/show_bug.cgi?id=58685, however, my approach would still be useful if the saved document is still empty so that no name can be generated from content. It would also reduce the risk to accidentally oversave a given file.