New York Times writer tested out Apple’s new Screen Time features on a teenager to see if they could really help people of all ages cut back on screen use.

And, according to writer Brian Chen, the feature worked brilliantly.

Chen worked with his editor’s 14-year-old daughter, Sophie, to test the technology. He lent her an iPhone X with the new iOS 12 software, which includes the Screen Time feature.

As the Deseret News reported, Screen Time is an iPhone settings feature that monitors people’s phone use. It shows people their stats for how much they use specific apps on their phone. People can also set time limits for how long they or their children use specific apps on their phones. When you run out of time, the phone will lock you out of your device.

Chen studied Sophie’s behavior for three weeks. He set a time limit for her on Snapchat, while he set one for his own Twitter use.

At first, Sophie spent time just staring at her screen once her Snapchat usage was up.

But, in the end, Sophie’s average daily phone use dropped from six hours in the first week to three hours in the third week.

“These early results should be welcome news to people who are growing increasingly concerned about long-term addiction to smartphones,” Chen wrote. “There have been other ways to limit use, including apps like Moment, which have many of the same features as Screen Time. But none of them have been embedded into a phone like Apple’s new software.”

Read more at The New York Times.

Apple announced the new controls back in June along with a slew of other settings, like the option for parents to monitor and control their children’s screen time.

There’s also a new Downtime feature, which can block everything on a child’s phone except for selected apps and phone calls.