Nautilus, with respect, all arrivals from KA, PD, and BRM to name a few were usually on RW06, and this isn't about a few extra track miles, it's about 5-20 min delays, which I should add are on top of the 5-45 min COBT delays.
Regarding 24 departures, GURAK SID is only convoluted when the RAAF are open for business and even then it is very rare to do the full procedure, once again I am sure most operators would happily accept a few extra miles over COBT delays followed by 20 mins taxi.
When GURAK was an inbound route for 03/06 yes. PEA/WAARP shut that down. If you look at the current STARS you will see using 03 and 06 for arrivals would be of no benefit. Now, if we had a "down the coast" inbound route through R155/160, that would be completely different. Traffic from the north inbound GEL JNB WAVES for 06 interleaved with traffic from the east on 03. Less track miles AND higher arrival rate.
Using 24 and 21 for departures in theory would increase departure rate, but how much effect would that have on arrivals? In practice, it wouldn't actually increase departure rates anyway. Departure rates are throttled because TWR can fire aircraft off one RWY faster than we can deal with them, primarily because they are not sorted in any way (eg Dash-8D launched 3 miles behind a F50 on the same SID
) Ideally you would have all GURAK departures off 24 to turn right, and all others off 21 to turn left (I don't know if that would create taxi issues) but if the departures weren't sorted it wouldn't really help.