According to @NotebookLM, OpenAI has expanded the character limit for ChatGPT chat customization from 500 to 10,000 characters, allowing users to create significantly more detailed AI personas. This update enables advanced prompt engineering and tailored workflow automation, supporting use cases like product management, education, and scientific research. The change is expected to drive greater adoption of AI assistants in business, as organizations can now build complex, role-specific agents with nuanced instructions, improving productivity and decision support across industries. (Source: @NotebookLM on Twitter, Dec 4, 2025)