@ellyxir automating my thermostat cut my heating costs by 10%.

Yes, most of the time my lights are controlled by a wall switch. But having an automated one in my laundry room is really handy because wall switches are hard to use when your hands are being used to hold a full basket. Or have an alert let you know that someone forgot to turn a light out.

The biggest benefit I got, though, was from data collected by sensors. You learn a great deal that can enable you to make things more energy efficient and/or comfortable.

@ellyxir and I love getting alerts when the laundry is done because I'm often out of earshot so I don't know otherwise.

Of course, I got fancy with it and have it alert only in the occupied parts of the house, but that's more because I could than because I must.

Monitoring can do great things. Because I added my own temperature probes, I was able to tell proactively that something was wrong in my refrigerator and didn't have to wait for food to spoil.

@ellyxir in my case, it's plugged into a Zigbee power monitoring plug. I have a #homeassistant helper sensor that considers the washing machine to be on if consumption is above a threshold, and off if below a threshold. When it registers as off, it sends alerts.

Other people use vibration sensors, or have a smart appliance with an API.