With Paper Tiger Filing System, do I have to index every single document?

Absolutely not. You can group like-documents together just like you would if you were using an alphabetic method of filing - basically the way that makes the most sense. The Paper Tiger just allows you to find the hanging file folders much faster and allows you to put multiple keywords in the database relating to each piece of paper within each file folder to use the power of the computer to find what you need when you need it no matter what you think you filed it under that particular day. It really works!