Hi @sourceCtrl,
If your app has 20 sections, you would need to set up your ad placements in the UI like this: 1.2, 1.4, 1.7, 2.2, 2.4, 2.7, 3.2, 3.4… up to 20.2, 20.4, 20.7
If you have any additional questions about this, please reach out to us directly at support@mopub.com with your account log-in and ad unit ID.
Thanks!