hybrid

From the 'Manage URL's' center, it say this:

"When you have less than 3 galleries per category, your traffic delivery is much slower than it normally would be, and the system doesn't work as well. The ideal number is 3-5 per category, and if possible they should be of different types to keep the traffic interested."

Now, to me, I cannot think of one logical reason why this is.

Can anyone explain this?