Product Managers process several terabytes of information on a weekly basis in the form of customer calls, Jira tickets, Slack messages, et al.
PM are also famously expected to multi-task (not multi-focus). Decision fatigue can get real and memory, long-form docs or comments in code can only help so much. Every PM needs a personal, private knowledge management system. More about this later. Here are eight docs that help me day to day.