Jaitsri is a section of middling length carrying a var alongside its hymns, and its position deep in the central stretch of the volume is characteristic of how the Granth reads to anyone going through it in order.
There is no development from one rag to the next. A reader moving from Dhanasri into Jaitsri does not find the argument advancing, because there is no argument being advanced. The same concerns return in a new musical setting: the name of God as the thing to hold to, the futility of an attachment to what will be left behind, the separation of the soul from what it loves, the uselessness of religious display, the necessity of the teacher.
Recognising this changes what kind of reading is possible. The Granth does not reward being read as a treatise and was not compiled to be. It rewards being opened, sung from, and returned to, and the repetition that frustrates a systematic reader is exactly what makes it usable that way: any section is an entry, because no section depends on the one before it.
The observance in which the volume is read continuously from beginning to end, over roughly two days, is therefore doing something other than following an argument. What is being marked is completeness, that the whole of it has been sounded, and the practice makes sense of an arrangement that a study of the text alone would find puzzling.