The chronological approach is drilled into us in elementary and high school. We start the story at the beginning and work on through, box to box, to the end.
A is always followed by B.
Later on in the workplace, we learn that A is sometimes followed by D or R and that going out of order - and thus creating a new sequence - can be beneficial.
Thus we don't wait until a draft is perfect before circulating it to others; we let a copy make the rounds early and benefit from the wisdom of colleagues. We don't expect to have all of the information before surfacing a proposal, but instead hold an informal brainstorming session with the recipient in order to ferret out possible concerns.
This doesn't mean that we've abandoned a linear approach. Our willingness to meander simply recognizes that there is a time to get off the trail and a time to return to it. Sometimes, the side trips are highly educational. They may even turn into shortcuts.