I can give a rough idea of travel times from USyd to the main hospitals of the clinical schools. (I'm doing this all from memory, and I'm not a USyd student, so I may be a bit off.) However, I'm quite sure a lot of time is also spent in the satellite hospitals of the schools, which can be some distance from the main hospitals.
Central: Royal Prince Alfred is across the road from USyd. Concord would be roughly a 20 min bus ride.
Northern: Royal North Shore is within walking distance of St Leonards railway station, which is 20 min by train from Redfern, the closest station to USyd. I think the satellite hospitals can be an hour or more from USyd, accessible by bus.
Western: Westmead is about 40 min by train from the city, and Nepean is about an hour from the city by train. I don't know how close the hospitals are to the railway stations.