For sites that depend on advertising revenue, impressions – the number of times each day an ad is served to a user – is an incrediblely important metric. But you have to be careful. Adding several layers of navigational pages between the home page and the content users want will definitely increase your ad impressions, but is it serving user needs? Probably not. And in the long run it will show: as your users get frustrated and decide not to come back.
The Elements of User Design by Jesse James Garrett