One URL per test
Generate several ads, but send them to the same page until you know the page converts. Changing both at once teaches you nothing.
Reuse the first five words
If the ad starts with "stop rewriting sales pages by hand," the H1 should start the same way. The generator can give you variants. You lock the match.
Keep a swipe of your winners
When a line works, save it. The tool is for first drafts, not for forgetting what already converted.