I use a combination of things. For me that has been the best option. I had been relying on the Alexa app presence as my go to presence sensor. It was very reliable until it wasn't. Twice it has stopped working in the last year or so. Each time after an update and the next update got it working again. The HE mobile has about a 80% success rate.
So I also added GeoFency, So using the HE GeoFency app along with Alexa app and HE mobile app and wifi presnce it has been very reliable.
I am using an IPhone but most of this is available for Android as well, I believe.
