🚀 go-pugleaf

You can write a script to replicate the behavior you describe whether or not the autoflow option is available. I use this function:

function DumbRunPages(theDoc, theStory) {
	// What makes this "dumb" is that default master pages are used.
	var uRuler = theDoc.viewPreferences.rulerOrigin;
	theDoc.viewPreferences.rulerOrigin = RulerOrigin.spreadOrigin;
	while (theStory.textFrames[-1].overflows) {
		theDoc.documentPreferences.pagesPerDocument = theDoc.documentPreferences.pagesPerDocument + 1;
		var backPage = theDoc.pages[-1];
		app.activeWindow.activePage = backPage;
		backPage.appliedMaster = theDoc.pages[-2].appliedMaster;
		var myPbounds = backPage.bounds;
		var myNewTF = backPage.textFrames.add();
		if ((backPage.name % 2 == 1) || (!theDoc.documentPreferences.facingPages)) {
 			myNewTF.geometricBounds =
 				[myPbounds[0] + backPage.marginPreferences.top,
 					myPbounds[1] + backPage.marginPreferences.left,
 					myPbounds[2] - backPage.marginPreferences.bottom,
 				 	myPbounds[3] - backPage.marginPreferences.right];
		} else {
			myNewTF.geometricBounds =
				[myPbounds[0] + backPage.marginPreferences.top,
					myPbounds[1] + backPage.marginPreferences.right,
					myPbounds[2] - backPage.marginPreferences.bottom,
					myPbounds[3] - backPage.marginPreferences.left];
		}
		myNewTF.itemLayer = theStory.textFrames[-1].itemLayer;
		myNewTF.previousTextFrame = theStory.textFrames[-1];
		myNewTF.textFramePreferences.textColumnCount = backPage.marginPreferences.columnCount;
		myNewTF.textFramePreferences.textColumnGutter = backPage.marginPreferences.columnGutter;
		if (myNewTF.characters.length == 0){
			theDoc.viewPreferences.rulerOrigin = uRuler;
			throw ("Permanently overset"); // This indicates a permanent overset condition so break out of loop
		}
	}
	theDoc.viewPreferences.rulerOrigin = uRuler;
}

Dave