What concerns me is that the original instruction did not appear to be based on much more than a wild @ssed guess.
Clearly, going from Six to Eight aircraft is a 33% workload increase.....or is it?
What appears to me to be missing from consideration is the "meta message" (the message being sent when you don't think you are sending a message) that is constantly being transmitted by ATC, taxiing aircraft, Circuit aircraft and arriving and departing aircraft.
The "meta message" is contained in voice procedure, standard of English, circuit behaviour and taxiing behaviour. As a YMMB flier who does the odd circuit to keep their hand in, it's pretty bloody obvious when things are getting too busy.
That is when I land and go home, not wishing to contribute any further to the confusion of kids who don't understand taxiing instructions, joining instructions, and whose wide circuits take them into the next state, and yes, we all started like that, but was the circuit always full of complete beginners?
To put it another way, if one of those sausage machine training courses is just starting, even Six in the circuit is going to be a handful, but come back Three weeks later and Eight or more plus arrivals and departures may well be doable for all I know.