I had a contractor come out and give me a quote for an in ground irrigation system. He proposes to water my landscape beds (trees and shrubs)with spray nozels and he would set them to water the landscaping with the same schedule and quantity of water that the lawn gets. Basically set the lawn sprinkler to encompass the beds. This doesnt feel right to me. I would think that a dogwood tree, japanese maple, crab apple, etc would be better off getting a much deeper and infrequent watering than what the lawn needs.

Even if I water the lawn deeply and infrequently that wont equate to "deep" for a young tree with roots 2ft in the ground and covered by a few inches of mulch. That frequent and shallow watering seems like it could actually be detrimental to the trees. What do people think? How would you handle this situation?