Hi,
Usually we do not use ad network, we only use to countries where we do not have specific agreement or if user already see specific ads.
Often we have a great loss with our campaigns, maybe for months we only pay users of our website without any conversion, and when it happens gives us a good gain, then our focus is on conversion, the more conversion more we can pay for our users.
The more advertising the user sees, the less conversions happens, then less we gain and less we can pay. Usually 95% of users do not wait for ads page loads, if user see 3 or 4 ads, this rate can be up to 99,9%.
Best Regards.