Uncle
As a "WestEnder" (Basically CPT - STU) I'll add that it is a very regular occurence to have you on a radar heading from first call on 134.75 until we release you own nav once at cruise around the STU area and hand you to Shannon.
The major east / west air route there is UL9 (there are a couple either side, UN14 for example) none of the routes are 12 miles apart therefore any opposite direction traffic MUST be on headings against each other, if you need to climb or descend thru.
From about 0700 to 2100 each day our mix of aircraft on that route can consist of any of the following:
Eastbound,
Overflights FL310+
EICK, EINN & EIDW outbounds climbing to FL330+
LTMA inbounds descending from FL330 to FL140
Westbound,
LTMA outbounds climbing FL130 to cruise
Westbound overflights
Dublin inbounds descending to FL240
Cork inbounds descending to FL300
Shannon inbounds descending to FL340
That's why we keep you on a heading!
We all strive that one heading will be enough all the way but as you know with wind direction and speed changing all the way up/down we sometimes have to keep "tweaking" you to mantain the track we desire!
Hope that helps.