X has enlarged his moves again. Just launched Custom Timelines - you can pin any theme in the homepage tab, and the official says it supports 75+themes. It's like your homepage has changed from 'One For You' to 'Multiple For You', each categorized by topic. The underlying logic is that Grok understands the content of each tweet and then overlays the original personalized algorithm. That is to say, even with the same "AI" topic, everyone sees it differently. Product manager Nikita Bier said this is a major project that will take several months. Start with iOS Premium users first, and Android will quickly catch up. From the perspective of creators, in the past, your content could only enter one "river" (For You), but now it has become 75 "tributaries", and the exposure path of accounts that deeply cultivate vertical fields is clearer. A general content account will be even more awkward because you can't squeeze into any river. This move is in line with the previous algorithm's weighted attention/cross-correlation content and the launch of Smart Cashtags - X is cutting the platform from a "unified information flow" into a "directed content network".