The coverage on my backyard irrigation sprinkler system is poor(dry spots). It currently has 3 zones and about 5 sprinkler heads on each zone. All placed randomly with no symmetry and different pattern heads from one side to the other. I've read a few online setups. Some reason real people on reddit give me more confidence than an article. How would you set it up? Also should the heads be in the lawn? Currently they are behind a divider that separates the lawn from a rock border. I live in AZ. Idk the pressure but one head in a corner throws about 15 ft.