Hey Suzi. Living in Carmel Valley for many years, I've gone through droughts more than once, and lost many trees because of it. In general, deeper watering less often is preferred, as it will encourage deeper rooting. Shallow watering often leads to shallow roots. If possible, you can divide the drip system, maybe water trees longer and deeper fewer times per week than roses or smaller plants. That, and mulch, mulch, mulch. It's raining here this morning, I hope it makes its way south to you.