Why not follow countries that ARE actually busy and implement their system and learn from their experience?
Umm, thats what METRON is;
Founded in 1995, Metron Aviation pioneered the advancement of air traffic flow management (ATFM), working with the Federal Aviation Administration (FAA) to develop the industry’s first collaborative decision making (CDM) platform for optimizing system-wide traffic flow. Metron Aviation provides concept engineering, advanced research, software development, traffic flow management, surface operations management, airspace design and environmental research and analysis solutions to the global aviation industry. Metron Aviation fuses advanced science and mathematics with unparalleled subject-matter expertise to turn groundbreaking air traffic management (ATM) research concepts into next-generation operational capabilities.
Recently, Metron Aviation was the recipient of the largest small business award in FAA history, System Engineering 2020 (SE-2020). Additionally, South Africa’s air traffic and navigation services (ATNS) began live operations with Metron Aviation’s ATFM solution this year, while Airservices Australia is in the process of deploying the ATFM solution to support its long-term gate-to-gate CDM vision.
HKF
As far as I can tell the noise abatement priorities are weighted towards arrivals rather than departures. If you think about it, 21/24 flight paths are almost the same as 03/06, e.g. a 21 departure is a 03 arrival.
The ten miles trail comes form required spacing for landing. At about 30-40 miles out if you are less than 10 miles behind and the same speed, the runway won't be clear when you need a landing clearance. You can't be slower than preceding traffic because you run out of slower speeds for each successive arrival. (I gather that in the US the RWY does not need to be clear for a landing clearance to be issued, but rules like that are out of ATC hands in Aus). Remember, for an arrivals sequence, the further apart I need to spread you out the more work I have to do. Likewise the more a/c we can land per hour, the less work I have to do, so I can assure you it's not laziness.
For departures the bottleneck is not the runways but the airspace out to about 50nm. We've done this to death in various other threads, but remember when your wheels leave the ground you aircraft becomes 3nm wide and 3nm long. When you call ML centre at about 10nm out, you become it becomes 5nm.
Personally I think the next thing to do is 'sequence' the departures. If aircraft are being delayed on the ground anyway, why not put then in the most efficient order? Rather than say 5 turbos nose to tail to the NE then 6 jets one after another to the north (146's and F100's in front of B737's as often as not).