Why should an advertiser upload all creative asset sizes that are available during campaign set up?

Uploading all available creative asset sizes allows Amazon DSP's optimization algorithms to test various ad formats and dimensions. The system can then automatically prioritize and serve the creative sizes that are generating the best performance (e.g., highest click-through rates, lowest cost per acquisition) for the campaign's objectives. This data-driven approach ensures that the most effective ads are shown to the target audience, maximizing campaign efficiency. Maximizing viewability is a goal, but uploading all sizes is a means to optimize performance, which includes viewability. Reducing setup time is incorrect; uploading more assets takes more time initially. Increasing campaign reach is also incorrect; reach is determined by targeting and budget, not directly by the number of creative sizes.