How can the constant traffic seen on Hubpages over a 12 month period be explained if there is no quota or similar control mechanism. Over 12 months a lot has happened on Hubpages. Hundreds of new pages have been added over 12 months, but the traffic remains the same, apart from a quota adjustment around 23 March 2014. Traffic should be increasing steadily as the new pages that are added gets new views, but the traffic is steady apart from the weekly cycle.
Recently, Hubpages added thousands and thousands of pages from Squidoo. As shown in the graph, traffic initially rose in response to the new pages. But after a week or so there was a dramatic pull-back to quota. Sure the 'pull-back' corresponded with Panda 4.1, but this is exactly what Panda is designed to do. It is a traffic control device to limit the share if traffic garnered by Hubpages. Low and behold the traffic recently returned to what it had been for more than 12 months. Once again what other explanation can be used for these changes.
If there is a Quota there are Profound Consequences
With a quota applied it means that new pages have to compete with pages already there. There will be profound competition for the limited 'pie'. Partially this occurs because Google will only show 1-2 results for the same site in the SERPS. But this also applies to topics and keyword sets that are not saturated. The penalty and control mechanisms lead to small ranking changes to keep the traffic within 'Quota'.
And you can't get over that!