airdualbleedfault - with respect I think you are still confusing movements with arrivals or departures. Wed morning TWR were firing 40+/hour departures. Remember all bar two flights out of PH are in an arc of just 135 degrees, and I don't think thats bad going (if the TWR didn't clump same direction departures together we could do better, but thats another story).
Especially in Perth's peak departure times-
The above same direction comment just got me thinking about the fact that once all the departing aircraft are lined up nose to tail on the 1 or maybe 2 available taxiways to the THLD holding points then ATC can basically only launch them in the order they are lined up on each, regardless of their departure routing/direction or type (TP or jet) and thus departure climb out speeds.
Just an out of the box thought, what if the last approx 3-500m of the taxiway was wide enough to be like a 2 lane road so that everyone was lined up as now nose to tail in the left hand "holding lane" but could then be called out of that line/lane by ATC so that they can be launched in any order ATC deemed best??? The order of the original taxiway lineup then wouldn't matter. As gaps form in the holding lane everyone just moves forward to fill gaps and allow following aircraft in to the back of the "holding lane" area.
That way they could launch say 2-4 similar speed jets one after the other then 2-4 T/props etc and so on so there would be less issues with a jet that was lined up right behind it overtaking a T/Prop on a similar/same SID or routing or a fast jet doing the same to a slower climbing one etc until they were further away from the airport where there is then more room to manoeuvre/ radar vector both laterally as well as vertically to maintain separation.
That might lead to an overall faster TKOf rate/hr as the time waiting for faster type to be cleared behind a slower aircraft that has departed ahead of it could be reduced as the climb speeds of each would be better matched and there would be little overtaking rate speed difference, eg jet behind a much slower climbing T/prop.
IE, Separation times could be closer to the minimums allowed as the speed/performance of that "departing group type" would all be very similar.
If 2-3 T/props go one after the other with say a left turn on routes heading in a certain direction then maybe the next 2-3 jets launched behind them could be those going right initially or further straight out before turning left etc.
I hope you can understand what I am trying to say. Just an idea.