A well-known Victorian gardening guru (Kevin Heinze, now dead) advised very strongly in his TV show that grass needed to be left longer in summer to "give it a chance" in the relatively tough conditions of intense sun and dry roots. That is, water retention was the issue. He then reminded people at the beginning of winter to set the mower lower if they really felt they needed to, but remember to jack it back up in summer.
Obviously the issues that led him in that direction are almost reversed in coastal Queensland. In Victoria, if you cut grass - even kikuyu - short in summer it will suffer, and show it. It can take quite a while to recover.
