What is your rule on how to stop an under-performing campaign?

I normally allocate a certain testing budget to my campaign, but I always end up questioning myself whether it is time to close it already.

Some campaigns start really badly for the first couple of days and get better after optimization while others only continue losing money on a bad offer.

Do you guys have any specific metric that helps you determine that enough is enough?

i usually separate “not enough data yet” from “the data is already telling me something.”

if spend is accumulating but the downstream events aren't moving at all, giving it more budget doesn't necessarily make the test more valid.

i'd rather look at where the funnel is breaking — click, lander, registration/lead, sale — and whether any individual sources are showing signs of life. sometimes the campaign isn't dead, just most of the traffic inside it is.