So I’ve noticed that some of the set altitudes for arrivals/approaches are a bit confusing and unnecessary. For instance I’ve seen an arrival into YSSY where it goes from 8000ft then to 9000ft then to 6000ft. What’s with the 9000ft? Also sometimes it will be set to 3000ft for a good 5-10NM which is a bit unrealistic for an aircraft to level out and fly 3000ft just before final. I’ve seen these on quite a few arrivals and approaches and so I’m wondering why they’re like this.