You don't always need complicated rules to manage your ads. Lots of our clients use ROAS (return on ad spend) metric as a main factor in optimizing their ad campaigns. It is especially effective if you're running an e-commerce store and have many different goods with various prices, so the Cost Per Purchase metric isn't exactly working for you.
So here is a rule that is simple and yet very powerful, it'll stop any ad sets that after spending $15 today have returned less than 1.5x in purchase revenue:
Try it yourself with our free 14-days trial and don't hesitate to contact us if you need any assistance ;)