3 things that quietly wreck CBO campaigns when people try to scale

Picked up a few accounts over the past year that were already running CBO and noticed the same three things keep happening right when someone tries to push a winner harder. Might be obvious to some of you but kept seeing it so figured I'd write it down.

Editing the live ad set too much is probably the biggest one. New creative, copy tweak, bumping budget more than like 20 percent, all of it resets learning phase and a lot of people don't connect the dots when results go quiet for a few days right after they "improved" something.

Second thing, old ad sets just sitting there from before. Picked up an account where the last person left three dead ad sets active and nobody noticed they were eating budget in the same auction as the new one. Worth checking Audience Overlap before assuming the new ad set is just bad.

Third, jumping budget up all at once instead of small steps. Going $50 to $150 overnight feels like the efficient move but it just throws you back into learning and you lose whatever stability you built up. Slower bumps every few days actually get there faster in the end, even though it doesn't feel like it.

What's the weirdest thing you've seen quietly tank a scale up? Feel like there's always something new.