How to find a powerful ad headline

Recently I was having a conversation with somebody who had read you should write 200 different ad headlines for an ad, and then choose the most powerful. I think there are several flaws in this approach...

• The odds are you'll end up choosing a headline you like, rather than one your target market responds to
• It takes a long time to come up with 200 unique headlines
• In the time it took to generate 200 headlines, you could have been testing different headlines against each other in real ads
• The resulting data will tell you which headline gets your target market excited, rather than relying on your own opinions or those of others (i.e. objective results versus subjective opinion)
  
• During testing you'll almost certainly make sales. Testing generates revenue, where as dreaming up ever more creative headlines doesn't
• After testing, you have something you know for certain will work. After wasting your time on 200 headlines, you won't

In other words, why waste time being creative when you could let the target market tell you what works? And continue to make money along the way? That's how I approach ad copy.