A few years ago when we converted a back grassy yard to the gravel garden, we removed most of the sprinklers and changed over the remaining ones to a drip system specifically for the few plants that were left in the area.
The main tree that shaded the area was this mature old pepper tree (schinus molle) that is very drought tolerant and was pretty much left to survive on rainfall. Since then it is starting to show signs of stress from the drought. There are lots of dead branches and foliage hanging down that will need to be removed when the tree trimmers come in the fall this year. For the first time I will need to put a sprinkler down there to give it a deep drink of water at least every month to get it through the summer and keep it healthy until the rainy season. This was not something I had anticipated due to the advanced age and type of tree which seems to be able to withstand any abuse in a native setting.
The rest of the gravel garden with the drip system is doing fine and hanging in there nicely.