For those interested, here’s my strategy for low battery use but reliable Home/Away activation:
I’ve set iPhone Locator polling to 15 minutes plus used Reactor scenes triggered by our Garage Door:
Coming Home - Garage Door Opens (Conditions: Home mode = Away, Garage changing from Closed to Open):
Leaving Home - Garage Door Closes (Conditions: Home mode = Home, Garage changing from Open to Closed):
This seems to work pretty well and not impact battery life negatively. I also Use night mode to mute location polling when we go to bed.