Speaking at Fortune’s Most Powerful Women Summit in Washington, D.C. on Monday, Alison Lewis, CMO at Johnson & Johnson, said: “Marketing has been transformed. What we think is going to work, doesn’t work. It’s always the surprising things that are off the charts,” Finding ways to respond rapidly and productively to those surprises, both positive and negative was a prime topic of the day for Lewis and her fellow Summit panelists. Here are a few of their insights:

1. The Truth Will Set You Free

Sometimes even a less than positive revelation can trigger needed change. When The New York Times found J.P. Morgan Chase ads on so-called fake news sites—some of which had offensive content—Kristin Lemkau, the bank’s CMO, took a dramatic stand and pulled the bank’s ads off hundreds of thousands of sites.

“We’d never asked how many websites our brand was on,” Lemkau recalled. Turns out the answer was 400,000. And that raised another question: Why were they on so many sites? She challenged her team to find out how many of those sites actually were getting clicks. Answer: about 12,000. And how many of those were sites her brand wanted to be near? About 5,000. They’re now back up to 10,000 sites, thanks to careful vetting.

There’s so much hyperbole out there, Lewis said. It’s hard for anyone to know where the truth is. But if there’s a bout of negative news she advises companies to “put the facts out there and the truth will set you free. Some will choose not to come with you, but those that do will because they like what you said.”

2. Trust Your Counter-Intuition

In May, when an Australian real estate mogul suggested posited the somewhat insulting theory that millennials aren’t able to buy homes because they’re spending too much on discretionary items like avocado toast, SoFi COO Joanne Bradford tapped into that controversy as a way to connect with the company’s millennial customer base: the online lender offered a month of free avocado toast to everyone who got a mortgage through the company. More than a hundred a media outlets jumped on the story and SoFi had three of its greatest months ever.

“What we realized is that sometimes we treat millennials too seriously. They like to be in on the joke of it, and the insight of it,” she told the Summit audience. The company received thank-you notes from customers who insisted that they could not only get a mortgage, “they wanted to have their avocado toast and eat it too.”

3. Don’t Drown in Data

There’s more data available than anyone could analyze and harness, Michelle Peluso, IBM’s first CMO, told the Fortune crowd. So “you need to “be really hypothesis driven to better use data. What’s the problem you want to solve most? Where people go wrong, you get so excited by what you have, you say I could do this and this and this,” she said.

Sometimes that means challenging conventional wisdom. Bradford said that her team thought it was reaching its customer base and getting quality clicks by advertising on smart millennial-focused sites, but a look at the data showed something different. They “found that ads were ineffective, even on premium sites. We cut all of our premium digital spending for the quarter and we actually saw increased results.”

What else works? Direct mail. “God forbid I say this out loud as a digital native, but direct mail is still important to us. It explains our offer fully on a one-to-one basis. We see all of our channels perform better when we drop our direct mail,” Bradford explained.

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4. Speed Matters More Than Ever

Perhaps the most important shift in marketing is the “speed at which we’ve had to move,” said J&J’s Lewis. For example, her team had just finished perfecting a six-second ad on Facebook, when they had to pivot to a two-second ad because their tracking showed that people were only watching for about 1.7 seconds.

5. Less Really Can Be More

Recently, Lewis and her team launched a light therapy mask as an anti-aging product in Asia. Normally they would have flooded the shelves and tried to move as much product as possible as fast as possible, she said. But this time, they tried something very different: Before releasing the mask, they had people sign up to get in advance. By constricting the supply, they created demand…and buzz. And that scarcity, says Lewis, is what drove massive success. “We got all these influencers and bloggers talking about [the product] because they couldn’t get it.”

And, don’t assume that more resources will lead to better results, SoFi’s Bradford said. “I try to take away everything I can from my team every day.”

She tells them they don’t need the resources they think they do, “because in that moment, people become much more resourceful.”