Ad Tester allows you to test thousands of ad combinations simultaneously. Rather than manually setting up different experiments, all you need to do is add placeholders to your site.
A "placeholder" is a potential ad location.
When you begin testing, Ezoic's system will use these placeholders to create new, customized ad combinations for each user. We recommend adding at least 10-15 placeholders per page. That doesn't mean 10-15 ads will show, it just means that the system has the ability to test various ad combinations using the placeholders provided.
Ezoic's A.I. automatically figures out the best ad combination for each individual user using data extracted from your site. The more options you give the system to test, the more customized the outcome, which means a better user experience for visitors and more revenue for publishers.
Regardless of how many ad units you create, the system will never show more than the permitted number in accordance with Google Policy.
Regarding your revenue drop - I would recommend checking out the following Support article to help troubleshoot why your revenue has fallen:
Troubleshooting EPMV Changes
If you cannot determine why your revenue has fallen after taking a look through that Support article, please feel free to open a Support ticket and our team would be happy to look into this with you.