I want to start with something that’s probably already happened to you. You sit down, usually the night before a new term starts or right after a teacher mentions an upcoming exam, and you make a study timetable. A proper one. Color-coded, maybe. Every hour from 4 p.m. to 9 p.m. accounted for, subject by subject, down to the half hour. For two days it’s great. You feel organized for possibly the first time all semester. And then something small happens.you’re more tired than expected, or a friend calls, or one subject just takes way longer than the fifty minutes…