I still don't understand why, but wanted to clear up the confusion you may have caused.
Let me give an example.
Shoreham to Le Touquet.
EGKA SFD ALESO LFAT
ALESO is your FIR boundary.
Shoreham to Caen
EGKA SITET LFRK
SITET is your FIR boundary.
I am not saying everybody has to do it that way, obviously, but these waypoints are in abundance. Just looking at the 1:500k southern chart, you have
BIGNO SKERRY ORTAC BORLO GARMI KOTEM NEVIL SITET XAMAB XIDIL KUNAV ALESO SOVAT DEVAL RINTI VABIK KONAN RAPIX GILTI SUMUM XAMAM
and that is just for the south coast! Fill your boots....
Not let's look at another reason for using these. Let's say you are doing Shoreham-Caen. You cannot go direct, due to D040. Here, SITET gives you a handy waypoint.
I guess helicopter pilots fly differently (they certainly seem to fly much lower down) but if you extend this to flying abroad generally, there are very good reasons for using IFR waypoints
for the entire route - as I have explained elsewhere.