I would start with a very simple question - why do you want to get more traffic from Audience Network?
The fact is that the Facebook algorithm in most cases truly works. Trying to push delivery more toward one channel or another (even though somebody gave you a good hint) does not necessarily mean it will work the same way for you.
Variables below have (IMHO) the biggest impact, however, final figures might differ significantly from advertiser to advertiser (or even from campaign to campaign)
Targeting / Settings
- Optimization (MAI x AEO x VO)
- Platform (iOS x Android)
- Audience (Socio-demo, GEO)
- video asset ratio (16x9, 1x1, 4x5, 9x16) and length
For the test, I would start every time with "Automatic Placement" , upload the best creative in as many formats as possible (16x9, 1x1, 4x5, 9x16) and spend at least a few hundred bucks to see what FB thinks is the right placement for your mix of goal / targeting / product.
For us (mid-core pvp game) Audience Network brings comparable CPI with IG and FB, but with almost 2x higher conversion to the payer, so no-brainer...
Below you can see a share of our impressions among channels with different optimization goals (data from the last 30 days).
Keep in mind that this is impression share, not spend. CPM on AN can be even 3-5x higher in compare to IG or FB.
9x16 is AN king for us. Since we are doing campaigns on a relatively large scale, we don't want to miss auctions even in square/landscape inventory, but closing them is usually the first step when doing optimization.
Length - does it matter?
The screenshot below shows the results of our test campaign (approx. 10k USD, France), where we were testing the dependency of assets format / length on where the video will end up. It's not really apples to apples - we didn't have the same 'creative concept' in different length cuts, but at least we got something...
A very short video (let's say up to 10 sec) is obviously not opening any non-rewarded video placement within the Audience Network ( boo-hoo, I really hoped there will be something like that). Anything between 24-30 sec goes to ANs rewarded video placement without any problem.
There's nothing much you can do about this one. Facebook with your targeting either has impressions on a given platform or not.
If you really want to get as many (or even all) impressions in AN try to reach out to your FB representative and ask for Bid Multiplier.
We've been told that this feature is deprecated and they are not white-listing for it anymore, but maybe you'll be luckier.
Sorry for giving you such a vague answer but hope it will help at least a little. Unfortunately, the only way how to learn what is working for you is to go and test it for yourself.
Good luck with that!