Another consideration is that domestically at most ports they will only check in your bags at T-3 hours max. This is due to limited bag holding areas. So if you allow a lot of time you may be sitting around waiting for a while.

Eg: xmas time i flew HKG-MEL in CX J. Late notice got told to come straight up to SYD so that was on QF domestic (CX flight was personal and couldn't be changed), non-linked PNRs, so I allowed plenty of time just in case of delays. Get to QF check in counter and she quite rudely refused to take me as it was still 4 hours till my flight. So i spent an hour on the floor near the J* counters, quite a comedown from cathay business!