[Lawrie]

"Add Placeholder" does NOT create a PDF. It only creates an entry in the database without a file, just like pressing "+" in the song editor and chosing "blank pages". Nevertheless such a blank page can be filled with some content using the annotation editor and can be exported as a PDF.

I prepared files "Set 1" ... "Set xx" that I use as separators. They are imported into the database with song titles like "--- Set xx ---" to separate them visually when the setlist is displayed and sorts them to the top within the # section of the songs tab.  I added these separator songs to an extra collection called "Separators" to simplify filtering.
In the beginning these files were PDFs, later I switched to use ChordPro. ChordPro files have the advantage that I can edit them on the fly in MobileSheets.

I shall explore this further as that is how I expected the feature to work, however I remember being both surprised and disappointed by finding PDFs, which I did NOT create by exporting them.  I will admit however, that it was some time ago, and being an old fart my memory may be deceiving me and perhaps it was only database entries I found.  I will definitely be checking this.