Looks like you are doing the right thing by the look of the "new larger trees".
Looks also like your climate/environment is conducive to Austrians as the unattended pines look great also.
The variable comes with drastic changes such as drought or flooding, etc.
As for the watering question options, I always choose to water less frequently and water deep as you mentioned prior to asking the question to get roots to track deep as opposed to shallow ones that are drought susceptable.
You are lucky to be able to grow Austrians well. In my virginity (vicinity
) we have very wet springs and Austrians always get tip blight (diplodia) and it eventually takes them out. They are seldom planted because of this these days.
