My experience in SA has varied quite a lot.
There's what I'd call the Mesecke model. One person to rule it all. All the power but also all the responsibility.
Final say on coach appointments, Squad Management, even Team Selection. Drives the junior program philosophy, player recruitment, player development, camps, clinics.
Basically oversees everything. But ultimately can be held responsible when things go wrong.
There's the split system.
One for Boys and one for Girls. OR one for younger age groups, one for older ones. West Adelaide are a current example.
Splits the workload, but can cause some divide, loss of accountability.
There's the Development Only role.
Employing someone to drive player improvement/development without the responsibility of management of personel, team selections etc. Hard to hold to account. The current model by most SA clubs right now. Relies on a Committee person or individual coaches to cover the parents, admin, squad management, player management duties. Cheaper option.
There's the by Committee system.
Volunteer based. Age Group Coordinators either Div1 coach or someone else who knows the game and the age group. Can work to a point but ultimately becomes messy as players move age groups and there's no program/system from 10s-youth league.
The most successful over the past 30-40 years in Adelaide has been the Mesecke system. While many clubs have found the Boys/Girls split successful too. Personally I don't like the issues the older/younger split can create.
The problem is there's at most a handful of people in Adelaide who can do this role and none can perfectly complete all that's involved. There's not a single Club in Adelaide willing to spend what would be fair and provide some safety to the person in the role.
Also worth remembering SA Clubs can range from as small as 30 teams total to 120 teams.