If you run an Echo System using multiple dots on separate accounts, you run into issues where the echo in a room will work quite well... but one in another room, that is not completely sound isolated, will hear the command and turn on the lights in that room as well. This is why you must name them differently and use the same system for all in a typical Smart home. I have heard of people having the same account in different locations (home and work for instance), and that will work as long as the lights are set up with the different names as well. But none work in a single home with separate accounts.
I suggest setting up each BULB with a different name, and allow for room Group names as well. as an example, 4 bulbs in the living room would be east lamp, west lamp, north lap and south lamp, to control each separately, then the four of them would be in the Living room group where you can tell each or all to turn on/off. I've tried things in several ways and this seems to keep things from getting backed up and temperamental.
All of this is moot if you can guarantee the dot in one room cannot hear you from another room commanding a different dot.
You CAN also change the wake word for each dot, if you use 4 separate accounts (as an example), that way one does not interfere with the other. But then you have Echo, Amazon, Alexa, and Computer to talk to for each room... Again, doing this requires the separate accounts. As of now, there are only 4 available wake words, so your limitations are from that perspective now... I guess if you can keep the 5th or subsequent ones form being near enough to hear a command from another with the same wake word... you could get more single system set-ups per home. It would need to be a rather large home but the possibilities do exist.