I understand your concern. The multiple page option takes care of the situation where you will get a mega page if you insert a very long document. On the other hand if you have a very large document it will create a page for very document page. You should ask yourself if that is what you want. I had a presentation of 38 slides. It will create 38 pages (not what I wanted).

I have not discovered an option to add the pages together into one document. This is my wish as well. If it were separate OneNote containers you would have the option to merge those containers. Since prinouts are inserted as objects (images?) you can't combine them into one large container. Too bad in my opinion.