Dowelly, Im only guessing but I think the idea of having them all in Perth and one or two in Mandurah is about making it easier for the greater percentage of breamers to commit to a one day event without having to spend heaps of bucks on accommodation and travel etc, and hence get a good number of entries. Also maybe it helps guys who also can't commit to a two day event or get a Saturday's off etc.
Personally I wouldnt bother coming to Perth at all if had the systems you have to fish.
Lucky bugger.....