I've noticed that creative performance and placement quality often work together. A placement that performs poorly with one creative can suddenly become profitable with a different message or landing page.
This is exactly why I never judge a traffic source after one campaign. Sometimes it's not the network that's underperforming—it's simply that I haven't found the right placements yet.
I think both campaign-level and placement-level optimization are important, but they serve different purposes. Campaign optimization helps you build a solid foundation, while placement optimization helps you maximize returns.
Something I've started doing recently is creating separate reports for my best-performing placements. It makes scaling much easier because I already know where the highest-quality traffic is coming from.
One mistake I made early on was focusing only on CPC. A cheap click isn't always a good click. I'd rather pay a higher CPC for traffic that actually converts than waste money on visitors who bounce immediately.
For me, optimization is like peeling layers off an onion. First I review campaign performance, then creatives, then devices, then placements. Each layer reveals new opportunities.
The more campaigns I run, the more I realize that averages can be misleading. Overall campaign metrics might look average, but when you break them down, you'll often find a few placements carrying the entire campaign.