Complexities of writing
Producing texts is a complex matter
It requires the producer to keep hold of a lot of different perspectives.
In order to change the structure of the text, one must be able to survey the text as a whole and as a structure;
in order to be explicit, one must be able to imagine what an actual or a typical consumer know and can understand.
To organize and finish the text one must know for instance what one think of the subject. In that sense one needs to be finished with the content before one can finish the text.