How Much Can You Test?

If we're just running one ad and it doesn't work, shouldn't we have a series of things so that we can shut some down or whatever? And i think some of that kind of, again, that sort of plays into your budget, like, how much can you test? You know, if you have a budget of a hundred dollars, you're not going to go out and test a hundred ads, because that's not going to give you significant results. But you want to still make sure that you're having enough different audiences, very different audiences.