All good points and gratefully received!
I don't think that I can create a WiFi NW just for the Shelly's at this time as I already have multiple SSID's for different things and I don't think it is practical for have one specifically for the Shelly's.
I DO though like the idea of addressing them by room number and it would make things quite clear.
Anyway, I do thank you for your thoughts and for sharing your knowledge. It has given me some more to think about!!! (I might piggy back the i4 and add a temperature sensor to it, for example. I miight as well if I am running a device capable!)
Regards
Matthew