Many publishers have asked the question "Since feed items often get displayed with many feed items on a single web page, can using AdSense for feeds jeopardize the status of my AdSense account?"
The answer is no. Having three ad units per page is a product specific policy for AdSense for content. Product specific policies can be read about here.
In essence, the variable ways in which feed items are displayed are controlled and optimized automatically by the AdSense for feeds application and the choices you make as a publisher in your AdSense account when configuring your AdSense for feeds ad units. This means we may automatically suppress ad impressions when we detect there are too many feed ad units being displayed, resize ads based on the size and length of your content, and adjust the ads that are displayed based on the device in which the feed is being read.