Ditto on the ditto.

I also add location and reason for being there to the date on my folders which helps to navigate through them all as well .. eg. date_work_location/ etc, etc.
But I can't imagine how tedious it would be to place all the correct type of images into their appropriate directories if you do it categorically as this chap does.

What if you were out an about on a general photography day and you took many multiple types of images, landscape, people, macro, flowers, abstract.. etc all on the one session??
I can see how that'd be painful to deal with at the Card to PC download phase.

The reason for marking each image with additional metadata is for the purpose of locating the category/genre/type/date of any image that you trying to find.
Your cataloguing software will locate all the images you are after based on simple search descriptions.