The AI wars are driving a more demanding work culture in Silicon Valley that some insiders worry is burning workers out. A " 996 " work schedule, in which employees work six days a week from 9 a.m. to 9 p.m., has been well established in China and is taking hold in the San Francisco tech scene. While Silicon Valley has long been known for an intense work culture, some companies have recently adopted the more rigid  996 work schedule . Nathan Lambert, a senior research scientist at the Allen