Let's ensure readers understand that 'the scenario'
Mr Smith put forward for Broome [per below] is not difficult for procedural D/C controller/s, rather 'explaining' in written terms the way these separation/workload issues are managed is the difficult part.
Let's say there is a VFR aircraft at 6500' going from south to north about 20 miles to the east of Broome at the closest point. At about the same time you have an IFR Kingair on descent from the east, inbound to Broome as well as local flights and circuit traffic. It's sky clear.
Do you still believe that there would be no extra workload for the controller at Broome if C was allocated rather than E?
It’s a fair question!
Let’s see if we can work through the scenario’s:-
Assumptions [worst case]
1. The crossing VFR [let’s call it VH-V.F.R]
- No flight plan lodged with ATC
- No navaid’s receivers on-board
- No PCAS, ACAS or ADS-B OUT or IN
2. The arriving IFR [let’s call it VH-M.S.U]
- VOR, LOC, DME, GPS
- No PCAS, ACAS or ADS-B OUT or IN
Broome
Airservices Australia - Aeronautical Information Package (AIP)
is equipped with:-
- 25NM MSA A022
- 10NM MSA A015
Lets assume Tower operate D/C up to A085, Centre C above
Conditions
- Information ‘Delta’ current, Runway 28 in use [worse case profile for the Beech, straight in approach], CAVOK
- + Two Cessna’s in the circuit
- + Two helicopters [one outbound, one inbound] to/from the NW
Difficult to display without terminal area maps [which both pilots and ATC will have in towered airspace], but let try to build the picture.
Google map will do for this purpose: -
Google Maps - may have to zoom out/in and centre so you are able to see Broome and the Great Northern Highway to the East
Broome International Airport is on the peninsula to the west of centre, scale 40 ish’ miles
Hypothetical transcript
0400z
CEN – TWR “estimate MSU, Broome 0430, inbound on the 090 bearing, assigned A090”
TWR – CEN “MSU, A090”
0410z
E.L.C “Broome tower, Helicopter E.L.C is Willies Creek A015, inbound received ‘Delta’”
TWR “Helicopter E.L.C, Broome tower, track direct Broome, maintain A015, report at Cable Beach”
E.L.C [reads back]
0412z
A.B.B “A.B.B Base, touch and go”
TWR “A.B.B, clear touch and go”
A.B.B [reads back]
0414
E.L.L “Broome tower, Helicopter E.L.L is ready at the Helipad, for a NW departure”
TWR “Helicopter E.L.L Broome tower, traffic upwind, a Cessna remaining in the left circuit, climb to A055, depart on track, clear for take-off”
E.L.L [reads back]
0415z
V.F.R “Broome tower gidday, Cessna 206, V.F.R is 35NM to the south east, tracking northbound, maintaining A065, received delta, request clearance”
TWR “V.F.R Broome tower afternoon, cross control area tracking northbound remaining at least 1NM east of the Great Northern Highway at all times, maintain A065”
V.F.R [reads back]
A.B.B “A.B.B base, touch and go”
TWR “A.B.B clear touch and go”
A.B.B [reads back]
0417z
A.B.C “Broome tower, A.B.C Ready runway 28 for circuits”
TWR “A.B.C Broome tower, follow the company Cessna early left downwind, clear for take-off make left turn”
A.B.C [reads back clearance]
E.L.C “E.L.C approaching Cable beach”
TWR “E.L.C, clear visual approach, join circuit close right base for the helipad”
E.L.C [reads Back]
0418z
A.B.B “A.B.B, base touch and go”
TWR “A.B.B, follow the company Cessna on crosswind, clear touch and go”
A.B.B [reads back]
0420z
E.L.C “E.L.C Right base”
TWR “ E.L.C, at the Helipad, clear to land”
E.L.C [reads back]
A.B.C “A.B.C Base, touch and go”
TWR “A.B.C, helicopter traffic on opposite base is for the helipad, runway 28 clear touch and go”
A.B.C [reads back]
0421z
M.S.U “Broome tower afternoon, MSU, 31DME inbound 090, approaching A090 visual, received delta [ATIS]”
TWR “MSU Broome tower, afternoon, descend 075, report established west of the Great Northern Highway for further descent”
M.S.U “MSU, A075, wilco”
0421z til
0424z [more circuit calls]
0425z
M.S.U “M.S.U is west of the Great Northern Highway, maintaining A075”
TWR “M.S.U descent A025 visual, report approaching”
M.S.U “M.S.U A025”
TWR “V.F.R, established clear of Broome controlled airspace, frequency change approved”
V.F.R “V.F.R Frequency changed approved once OCTA, seeya”
TWR “ Cheers”, break A.B.B clear touch and go”
Etc Etc
In the illustration above, the two aircraft that conflict at 20nm East are resolved using only those transmissions above in
red. Easy
and SAFE 
Worthy of note, controllers have published separation diagrams at the ready that provide them quick reference to VFR geographical verses IFR route and distance separation options.
Add to that the fact that the local controllers develop in-depth knowledge of the topography, and the ‘solutions to most tracking and separation problems.
Do you still believe that there would be no extra workload for the controller at Broome if C was allocated rather than E?
Far better to have a local controller know what they are doing is right, apply the solution with a minimum of frequency use, rather than a non-local [but competent] pilot’s trying to work it out on the fly at short notice, broadcasting over the top of ATC trying to work out how to miss each other.
If I have got this little scenario wrong, ATC contributors will correct my mistakes.