M-A-C
Unfortunately, you will have noticed by now that some ATCOs do not understand that the overall task loading (for want of a better phrase) is a combination of level of traffic/complexity/local operating procedures/local airspace restrictions etc etc...
Some ATCOs like to believe that because they have a complex piece of airspace, they are working harder with only one or two A/C at a time, whereas others believe think that because they have lots of A/C (even if in very simple airspace) that they are working harder. (Not talking specific sectors here, just stating what some people believe).
If only 'task loading' was as simple to work out!