In the world of Banner Exchanges the concept is sometimes called Perpetual Motion. I will explain it. Lets say you are involved in the typical 3: 2 banner exchange programs. That means that you display 3 of the exchange’s banners for every 2 of yours displayed. The uneven exchange allows them to sell the banner space and run their business.
Perpetual Motion is the idea (or ideal) that any visitor that clicks on your banner and visits your site must see enough banners to generate the next visiort. An example. Say 1000 banners are displayed on other people’s sites and the click-through rate is 2.5%. This means that your site gets 25 visits.
If you look at a single visitor, you find that on average it took 40 banner displays to get the click. 40 banner displays on other people’s sites means that you have displayed 60 banner exchange banners on your site.
For Perpetual Motion to work each visitor must see 60 banners.
Is this possible? Probably not but the closer you get to the Perpetual Motion number the better your banner exchange program will perform for you. You can do things to optimize. Better targeting can raise the click-through rate. Pages can have more than 1 banner. Content can have the average visitor visit a large number of pages.
I hope I’ve explained this clearly. How do you measure this kind of advertising now.
Besides generally lower click rates these days, the main challenges would come from the banner exchanges themselves. They would need good enough reach to avoid quick banner burnout, have good enough placement on semi-uncluttered pages to be seen and clicked, and bring in the right kind of visitors for your site. Moreover, there is the issue of displaying random freebie banners that make bulk RON buys look elegant in comparison. None of these concerns are trivial, and I am not sure how many exchanges have the quantity and quality to facilitate those kind of results.
The click rates and the session lengths would have to consistently hit on the high end, because variability on the low end would bring things towards a halt. There might be a chance for perpetual motion in slow motion if the visitors come back on a regular basis, bringing new visitors every X amount of days. I have seen this to some degree on a few niche sites in niche exchanges (regular supply of fresh visitors in, minimal amount of visitors out), but your mileage may vary.