Hose Timer in a (mostly) always on application

I am considering using a Hose Timer to control an Orbit 62100 Yard Enforcer (https://www.amazon.com/Orbit-62100-Activated-Sprinkler-Detection/dp/B009F1R0GC/ref=sr_1_1_pp?s=lawn-garden&sr=1-1). I’m using the Yard Enforcer to keep Great Blue Herons away from the fish in our pond. The Hose Timer will be on for most of the time except when we are in the yard or when our lawn guy is there.

I talked to a helpful person at Rachio’s telephone support. He said the battery life of the Hose Timer would be significantly reduced in my application, but he couldn’t provide an estimate of the battery life.

Has anyone tried anything like this and can provide a rough estimate of battery life (assuming high quality alkaline batteries)? I’d be happy if I could get 1 or 2 months.

The app has tons of opportunity to be so much better. I also have a Yard Enforcer and also submitted a feature request for a “normally on/off” for the valve setting.