I'm up in Brisbane so our temperatures and humidity are similar, if not a little more extreme than Sydneys. I find that the water that individual trees use varies greatly amongst my collection. My trees receive full sun from around 9am in the morning until 2pm in the arvo at this time of year. I have a small shade sail over the shohins which provides less intense sunlight from about midday and even so, they all dry out a different times. The rate at which a pot dries out depends on a number of factors... the size of the pot, the condition of the root mass, the health and vigour of the tree, certainly the soil mix, the amount of foliage on the tree, the time of year, the trees exposure to the elements...
So it's important to know if the tree actually needs water or not and not to just water for the sake of it.
As you gain experience and familiarity with how your trees perform under different circumstances you will be able to tell whether a tree needs water instinctively, through obervation, the trees weight in your hand and it's appearance.
