I am running a vehicle routing problem analysis with two routes, 56 orders, and four depots (a beginning and ending depot for each route). I have designated the starting and ending depots, and drawn route zones for each route which contain the orders currently on the routes. My goal is to reassign orders to improve efficiency. Upon changing the route zones from "hard" to "soft", the orders designated to each route did not change; however, the sequence for one route did. It reduced the distance by two miles, and the time by five minutes. I have attached PDFs of the two variations of the VRP analysis. The ending depot for the southern route (the one that changed) is below order labeled 37, but kind of hard to see. I am using StreetMap Premium for my network data set.
I know the distance/time change is negligible, and I am not concerned with it. What I am concerned with is the reason why this happened, which I do not understand. I thought route zones affected the order assignments to routes, not the sequence. I am presenting this information to members of the accounting department at my company, and I need to be able to answer why this happened/how I came up with the proposed changes. I am pretty new to Network Analyst, so any help would be greatly appreciated!