I don’t know Melbourne’s specifics. But in my experience elsewhere short curved RNPs are great for number one in the sequence or multiple in a row, but the moment you get someone unable to accept the RNP or are trying to use them from different directions (see YPAD RWY 05 RNAV X / W) you will lose capacity.
Because the approach is curved, you have to pull the trigger on the approach clearance before the aircraft has turned into the final approach wind. You then don’t have the ability to vector without canceling the approach. It’s very difficult to use speed control effectively when aircraft are pointing in different directions experiencing different winds and different closure rates. Thus you need to play it conservatively and that reduces capacity.
Ask for direct tracking if you want it. We’ve been told
numerous times just leave you alone unless it’s needed.