What's your biggest frustration with A/B testing ad creatives?

I built PickAd, an ad creative testing platform, to solve a problem I kept running into: wasting ad budget to figure out which creative works. Curious to hear from other makers and marketers here.

When you're testing ads, what frustrates you the most? Is it the cost, the time it takes, the lack of real human feedback, or something else?

Would love to hear your experiences. It helps me make PickAd better for everyone.