Why sprinkler zones matter before sod
New sod needs even coverage. If one zone is overloaded, heads spray weakly and corners dry out. If one zone mixes rotors and sprays badly, the lawn can receive uneven water even when the controller looks correct.
What a professional still checks
A real design uses measured gallons per minute, pressure, head spacing, valves, pipe size, backflow requirements, and local rules. This planner is a conversation starter, not an engineering drawing.