Good catch on that "standby" mode that was enabled by default in V10. I am surprised tesla would auto enable an option like that without saying so. I turned it off after reading your other post when you made it, just on principle. I dont mind waiting extra time on using summon.
I too was experiencing a big loss, ~12 miles per day. Sunday I rebooted the system, you know tweaking her steering nipples and turning her off , and since then things appear to be back to normal. So if you haven't already, I'd suggest a reboot of the system.