I'm using an ISY (Universal-Devices.com) with a portal which allows up to five accounts. Each group of Echos (3)/Dots (7) is registered to a different account.
So I can ask Alexa to, "turn the light on," and only the light in the room I'm in turns on. If I want to control a device in a room other than the one I'm in, then I do need to name the location, for example, "turn on the kitchen light," if I'm not in the kitchen.