The Guru Granth Sahib is not primarily encountered as a book being read. It is encountered as a volume installed in a room, attended through a day, and sung from.
A gurdwara's day has a shape. The volume is brought in and installed in the morning and taken to rest at night, and between those points there is singing, there is reading, and there is the taking of a verse at random as the day's reflection. Congregations gather, food is prepared and served to everyone present without distinction, and decisions of the community are taken in the volume's presence.
Describing the rhythm is legitimate and useful. Setting out how to perform any part of it is not this atlas's to do, and the distinction is worth stating rather than assuming. A reference work that renders a living observance as a set of steps produces something that reads like an instruction manual, and instruction in a living tradition comes from that tradition.
What the rhythm explains, for a reader trying to understand the volume, is why its organisation looks the way it does. A book that is opened at a point, sung from, and closed, and that is present in a room all day rather than being studied in a sitting, does not need to be arranged as an argument. It needs to be findable, complete, and always the same, and the Granth is all three.