WHULorigan
Emperor Mongoose
Of course you might also be in a different subsector that is closer then the other side of the subsector. Also, might take into consideration jump routes when placing institutions of higher learning, if one is say a jump-6 from anywhere else but another is only jump-2 from multiple worlds which is more likely to be utilized?
Yes. There is nothing limiting people to discrete contained subsectors, only that general distance scale.
And travel is not always as easy as getting a liner or trader (or even a packet ship) going your way from your homeworld. You may need to travel to an intermediary world where you can "pick-up" a ship along a travel-route going where you want to go.