Bearing in mind this is the observations of a clinic patient. At the CMHC I was originally at with my Psychiatrist, it seemed to operate on three levels - there was the Acute Crisis Assessment Team, the outpatient clinic and then inpatient unit connected to the local hospital.
Acute crisis assessment was typically managed by a social worker and Psych nurse for the initial assessment, they allocated the urgency of the case (eg, must be see within 24 hours versus can be seen within a week) and then a registrar under the supervision of one of the lead/consultant Psychiatrists would do the actual intake. I got accepted into treatment at the clinic under a different scheme so I'm not entirely sure what happens if you are considered an acute crisis case in need of immediate stabilisation (I've mentioned before I was unwell and unstable at the time, but not to the level of being considered a crisis case).
From what I did observe:
There was a medication clinic, presumably for those under community treatment orders, that was run 2 days a week by Psych nurses, but the patients had to have their medication particulars checked and signed off by their treating Psychiatrist first. I'd also see some of the Psych nurses and social workers heading out with packs of medication, so presumably they did home visits as well.
Cab vouchers were/are available for those who are legitimately unwell enough to travel any other way, but that was at the discretion of Medicare itself and abusing the privilege could mean no more vouchers.
A walk in clinic was also available, but it seems to have kind of depended on how long you'd been with a particular Psychiatrist as to whether they would see you or whether you had to see one of the Registrars (walk ins were also basically for emergencies not just dropping by for a nice little chat).
If your appointment was for 30 minutes, and you turned up 20 minutes into the start time of your session then generally speaking you'd get the last 10 minutes but no more. If the Psychiatrist themselves were running late then you still got your full session time.
If you decided to stroll in an hour after your appointment time had been and gone, and still demanded to see your Psychiatrist (the girls on the desk had the patience of saints sometimes when trying to explain this to some of the less functional patients) you were given the option of re-booking or waiting for an available registrar.
Miss three sessions in a row and you were removed from the books. It was then up to discretion of the treating Psychiatrist to either reopen your file if you wanted to return, or to request that it remained open.