Great product…just wanted to delete my suggestion
That’s what a master valve does. Do you mean something different?
I wonder if @Powers89 is talking about allowing the water to be on even when the sprinklers are off. Maybe the water is going elsewhere such as a water feature, hose bib, or something else? The master valve would not allow for that. In my opinion, the disadvantage to that is power would probably always be applied to the valve to keep it on, not a huge draw, but some. Also, if a master valve is also used, I am not sure that enough power would exist to run three valve.