In an internal memo seen by the New York Times, the Google cofounder told employees working on Gemini, the company’s suite of AI products, that he recommends being in the office “at least every weekday” and that “60 hours a week is the sweet spot of productivity.”

He also warned against working more than 60 hours a week, saying it could lead to burnout, while calling out those who work less.

“A number of folks work less than 60 hours, and a small number put in the bare minimum to get by,” Brin wrote in February. “This last group is not only unproductive but also can be highly demoralizing to everyone else.”

A source close to the matter declined to comment, but the Times said the memo doesn’t signal a departure from the tech giant’s official policy for employees to work in the office at least three days a week. Recently, Google said staff on some teams will have to come into the office more often, though did not specify which departments would be affected when asked by Fortune.

Brin’s exhortations highlight the urgency to develop artificial general intelligence, or AGI, which is AI that’s as smart as or smarter than humans.

“Competition has accelerated immensely, and the final race to AGI is afoot,” he said in the memo. “I think we have all the ingredients to win this race, but we are going to have to turbocharge our efforts.”

Brin added that Gemini staff can boost their coding efficiency by using the company’s own AI technology.

The memo is one of the latest indications of his shift to a more hands-on role. In 2019, Brin and fellow Google cofounder Larry Page stepped down from their daily executive duties at parent company Alphabet.

But OpenAI’s release of ChatGPT in late 2022—and the tech sector’s rush to generative AI that followed—inspired Brin to get back into the mix. Since returning, Brin has also spent a lot of time at Google’s DeepMind AI division, according to the Times.

Last year, he acknowledged he “kind of came out of retirement, just because the trajectory of AI is so exciting.” That also coincided with some high-profile gaffes in Gemini’s AI, including an image generator that produced racially diverse Nazis.

Meanwhile, tech companies and corporate America overall are emphasizing in-person work. Amazon, AT&T, and JPMorgan Chase, for example, have told employees to work in the office five days a week. And President Donald Trump has ordered all federal workers to return to the office five days a week, too.

A version of this story originally published on Fortune.com on Feb. 28, 2025.

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