Actually, most of our route design and procedures are designed to move individual aircraft as easily as possible for a number of reasons.
The routes are designed for worst case i.e. routes are designed on the assumption there is always someone coming the other way. That means you always get the routes you were given, and usually unrestricted climb/descent whether there is traffic or not. If there is no opposite direction traffic, you get shortened.
The less work each aircraft requires, the more aircraft a controller/sector can deal with. You're paying our wages as well as your fuel bill and any controller has a finite work rate. If the workload is low, I can assess/procure shortening.
Systemic separation is safer then tactical. Rather than try to vector to separate each inbound and each outbound aircraft, SID's and STAR's are given that automatically provide separation. Its also more predictable for pilots.
Overall, though each aircraft may get suboptimal routing, traffic as a whole is optimised (as much as possible).
Last edited by Nautilus Blue; 28th Dec 2012 at 07:31.