I always assumed it was smart enough though not to do it when it's on battery as it is very likely that the device is also in a confined space, such as a laptop backpack waiting for the trip to the office next morning.

If I have it sitting on power and thus likely just on the top of the table and I have auto-updates on, sure do them when I'm not around as long as they are updates that can run unattended. Note the "if auto-updates are on" part, which luckily you can still disable on MacOS.