By default, Proper ads refresh every 60 seconds. This complies with demand partner limitations and maximizes the earning potential of each ad slot on the page.
Calculating The Value of A Refresh With RPM
This is the revenue per mille or revenue per thousand page views. Here is the calculation:
RPM = (Revenue/Pageview)*1000
RPM vs CPM
CPM is the cost per thousand impressions; whereas, the RPM is the revenue per thousand page views. In short, CPM is used to determine the value of each individual ad impression, while RPM can be used to determine the value of each page view on your site - which includes the sum of all ad slot impressions on the page.
Ads that are always in-view, such as sticky or adhesion units, may be refreshed every 15 seconds due to high viewability.