If you walked through the Water-Use-It-Wisely site’s Plant Watering Guide linked to in the drip calculator, you should have seen a table like this.
Note that the root depth for trees is typically 24-36 inches. You have 15" for your root depth, which will cause you to water more frequently. Mine are set to 30" for my established trees. After that tweak your crop coefficient if you don’t like the frequency (higher CC means more frequent watering).
Your watering duration is going to get longer after that change, which you probably won’t like. Two 1GPH heads on established trees is not sufficient, regardless the controller that you use. The goal is to water the periphery of trees and shrubs as uniformly as possible, and you can’t do that with 2 heads. I have three 2 GPH heads on each tree and my trees should probably have more. At minimum use heads with a rate higher than 1GPH so your runtime doesn’t get ridiculously long. For reference my runtime is 5 hours with three 2 GPH heads on each tree, so I deliver 30 gallons per watering about every 9 days. As I type this I think I need to bump up my root depth and deliver more, but right now it’s working for a 3 very well established Ficus trees and a couple of Brazilian Peppers. My 30 gallons are recommended for a tree with a 7ft canopy. Again, this information can be found at the ‘Water-Use-It-Wisely’ site.
For the shrubs follow the same procedure. Go through the Water-Use-It-Wisely site to pick the right root depth and amount of gallons that you should deliver.
Make sure that after you change the root depth and any other settings you run through the drip calculator again! The ‘inches of water’ will change in the Rachio app. and that will change the values that the calculator recomments.