Tip from the Pilothouse team:
Focus creative testing on 1x1 sized creative, but use a separate, consistent image for Story placement across all ad tests to speed velocity of testing.
Automatic placements are a must for testing and scale – which means you either need to build story placements for each creative test (slows down velocity) or if you don't include a story placement you'll have the automated janky background fills.
🔑 The Key:
Since story placements are generally such a low % of impression share, it won't make or break the creative test, and since the story creative is consistent across each test, it won't impact the data of the split test.