Since 80% of plants in retail nurseries (even here) are from more "typical" climates like England, continental Europe, Japan and southern China, they must be irrigated or die, at least here. For more xeriscaped landscapes, at least institutional and commercial, irrigation is standard practice. Many systems are on an ET (evapo-transpiration) schedule modification program. This automatically changes the watering duration depending on weather factors - warmer/dryer = longer cycle (more water).
Yes, a Mediterranean climate receives 90+% of it's rainfall in their cool winters, therefore, wet not dry. Or at least as wet as it gets.
This comes from a more 'landscape maintenance' point of view than a 'gardening' point of view, but the watering practices are essentially the same. I know it seems sort of counter-intuitive to cut back on water when it gets warmer and drier. But, if that's what the plants genetically "expect" then why not give it to them?
