I edited the answer there to include this...
If you wish to have multiple iterations of a layout printed on one sheet.....
- Set up a single page file containing 1 of the items (as described previously).
- When all the text is correct, export to a high quality single-page PDF.
- Open a new InDesign document the size of your output (A4)
File > Place to place each page of your PDF as an image.
- You can then position the PDF images however you'd like on one page.
- Simply print this "ganged" page. The original PDF data will be used for output.
If edits are then needed to the postcards... edit the single page file and output to PDF again. Open the "ganged" document, update the links, and print.
While it's not very commonly something one would think of for InDesign, a 2-file workflow can be exceptionally helpful if you need the gang items.
The reality is you don't even need a PDF. You can place InDesign pages into another InDesign document. So you could theoretically skip the PDF entirely. I find using a PDF in this manner as sort of a "fail safe". If something where to happen to the original file, or edits to the original file were incomplete, the PDF helps identify when output was generated last. But that is, admittedly, my preference.