Aircraft movements ...
Scuse my simple maths folks, but just because a unit has more movements, doesn't mean that it is necessarily busier.
That was one of the glaring unresolved problems with the model. Traffic 'volume' was hugely weighted to numbers of aircraft, but it didn't actually take 'volume' into account.
If all the sectors are small 60 mile sectors then each aircraft may only be on freq for 10 minutes.
However, it is worth remembering that some units have 200 mile sectors where ac can be on sector for 30-40 minutes.
So, the Q is .. if I have 15 ac on freq for 30 minutes each, am I working more or less than a short sharp shock sector with 45 per hr TSF at 10 minutes each?
The model would tell you that I am working at a third of the other sector ... which is pish ! And the stains on my trousers prove it !!
The model and grading were crap and divisive and it is a pity that more people did not bother to try and grasp the flawed maths behind it.