A week of lessons or tasks — set the first bell and the times fill themselves in
A timetable is a promise about time, and its usefulness comes almost entirely from being visible. A week written down and pinned up settles a hundred small questions before they are asked — what comes next, what to carry, when the gap falls — and it does this for everyone who can see it, which is why classrooms, hospitals and workshops have used the same grid of days against hours for well over a century. The form is old because it is hard to improve: the eye reads a column as a day and a row as a time without being told.
The parts that go wrong are usually the joins rather than the blocks. A schedule with no gap between one thing and the next assumes travel takes no time and that nothing ever overruns, and it fails on the first day. Breaks are not slack to be squeezed out; they are what lets the rest of the plan survive contact with an ordinary morning. The same goes for the end of the day: a timetable packed to the last minute leaves nothing for the thing that always comes up.
Colour is worth using sparingly and consistently. One colour per subject, or per kind of work, turns the grid into something readable at a glance from across a room — but a chart where every cell is a different shade carries no information at all, only decoration. The most useful timetables tend to be the plainest: a handful of colours that mean something, generous white space, and text large enough to read from where it will actually hang.