I agree with CJay,
Corner block back yard cut offs are quicker, easier and have the better profit margin. Although having said that, they are hard to get hold of, not many come on the market.
However I do believe there is still money to be made with battleaxe back yard cut offs within 10km of Adelaide City CBD, the rental demand must be high, and vacant land must be scarce, plus nearby to services/amenaties etc, as always good due dilligence, and knowing your end value by looking at comparable sales, so as not to spend too much to purchace in the first place.
In some areas, repeat some areas, hammerhead developments are quite acceptable. I've researched sales data for a part of Marion council area and found NO evidence that the hammerhead blocks of land sold for less or took longer to sell than street frontage courtyard-size blocks. Similarly, there was no evidence in the data that new hammerhead houses sold for less or took longer to sell than street frontage courtyard houses... food for thought...
Paul