requesting descents....
As My northern neighbour has eloquently stated...our job as ATC's is the Safe, orderly and expeditious flow of air traffic through our "patch".
It may or may not need to be pointed out that it goes in that particular order too, ie direct tracking gets last priority unless it helps with an immediate traffic confliction.
Back to the subject, the thing that really irritates me, especially when busy (and when isn't it here?) is having pilots nag for descent, be given "xxx descend to Fl200..." and have them then sit there for up to 30 odd miles before deciding to tip it over! (Airbus pilots in particular take note)
Yes I know that those glass cockpit thingies are hassling you but if you are not prepared to go now, don't ask, or do as some do, "request descent in 20 miles", don't know about anyone else but I am perfectly happy with that.
ps most of us issue "when ready" or "pilot discretion" when we mean just that...if we DON'T say it we don't mean it.