X rolled out Custom Timelines this week, a long-awaited tool that lets Premium subscribers pin topic-specific feeds right to their home screen. Nikita Bier, X’s head of product, called it “one of our biggest changes,” powered by Grok analyzing every post for relevance. Users swipe between these streams—over 75 options strong, from AI and cryptocurrency to soccer and K-pop. Early access hit iOS first; Android follows soon. Bier announced the launch on X, posting a demo video. “It’s powered by Grok’s understanding of every post with the algorithm’s personalization—meaning every timeline is made just for you. And it works even better when it’s a topic you already engage with,” he wrote. His post racked up thousands of likes, signaling real appetite. This isn’t keyword matching. Grok reads content holistically, assigns labels, then tailors based on your habits—no hashtags required, as an X representative told TechCrunch .…