Welcome to Dorico, Sadhaka!
That’s an interesting idea but I don’t think it really helps much, because you would have to change the order in which the music “flows” through the pages to jump out of sequence to the last page and then jump back again. You could do that, but it seems to me like you would just be swapping one problem for a different one.
This should become a lot simpler when you can start a new flow in the middle of a page and automatically insert the flow title etc without doing manual overrides - but that isn’t implemented yet.
Another aspect of all this is that people really seem to like tweaking the format of the project before all the music is entered and the page breaks are stable. There is a well known saying in computer programming that “premature optimisation is the root of all evil”. It also applies to document creation - though WYSIWYG products like Microsoft Word etc have led most people up that garden path! Dorico tries to separate “creating the content” (write mode) and “formatting the document” (engrave mode) but it can be hard to break the habits of a lifetime and start working a different way.
Actually, really large-scale document creation has always worked best the “Dorico way” - try creating say 10,000 cross-references and a similar sized index in a 1,000-page document using the menus and dialogs in Word, and you soon learn the limitations of WYSIWYG compared with a completely text-based input format! But most Word users probably consider a “large document” to be 10 pages, not 1,000.
Of course in music theatre people need to do frequent updates to the music - but even then, does saving half a page of paper in the printed parts really matter, compared with the amount of time and trouble it takes to save it - especially if that version will be thrown away and replaced by another one in a few days anyway?