Googlebot Rule of 4

Do you have a question? Post it now! No Registration Necessary.  Now with pictures!

May be a fluke, or at least not widely applicable,
(or even a well-known behavior I never heard of)
but I note for my own future reference:

While rearranging my web stat reporting, I decided
to print out a per-URL frequency of visits by
Googlebot over the last few months. The visit
counts binned surprisingly close to perfectly
into a few sizes.

The root and robots.txt were visited X times.
The first-level directory URLs were visited X/4 times.
The next most common visit count was X/16.

Possibly a feature of visit frequency being related
to # of incoming links, and using a hierarchical
navigation system, where every page links to the
root page, every third-level page links to a parent
second-level page, and so on.

Site Timeline