Just curious about how long would a candidate be expected to finish one's doctorate in different countries?
How does the system go in different countries (e.g. scholarships)?

Here in Australia, a full-time enrolment = 3 years stipend for living expenses.

It is then expected for students to finish around that time as they will need to self fund after that.

I don't know that saying the length of a PhD here in Aus is 3 years is all that accurate.
I don't know a single student that has completed their PhD in 3 years (even the guy who got his first post doc at Harvard.....).

In the "Framework for best practice in Doctoral Research Education in Australia" enrolment is defined as at least 3 years and then goes on to say that the duration for individual candidates can vary.

I think its fair to say that a student would generally be expected to finish in 3 1/2 to 4 years.

I was automatically enrolled for 4 years at my university.

I suppose if you were lucky enough to fall into the right project, with everything working well for you, it is possible to squeeze into that 3 year time frame. But I don't think many projects are like that and I don't know that you'd learn as much from a "come in and just churn out the results" type project anyway. Sometimes you learn the most when things are seemingly at their worst!

You are right that the scholarships provide for 3 years, although the 6 month extension following that is almost guaranteed.
(But not every student is on a scholarship either, there are 2 full fee paying students in my department alone.)