There is a lot of reason to what is posted here. If you were an HR professional for example, you would probably be filing your cards in a more complex manner, since that is what you would be sending rather frequently. As such you would also have more cards on hand. If, on the other hand, you send out a few per month at the most, I would simplify it - have fewer folders to go through. It is much easier to make a selection from a batch of cards you pulled from a folder and are now looking at them in your hand, rather than skimming through folders labels.