Usually with a multi room setup you will plumb a bunch of tanks together and have a fill valve on the outside of a building somewhere to be filled (if talking rec/med grows) from a truck. From there you will run a line and T off it to each room with its own controller. Most of the time a Co2 company (again if rec/med) setup will supply everything, including the controllers, run all the lines, setup a fill schedule, and give you all the tanks and regulators on a lease. Ends up being nice for that setup since you will never fhave to fuck with it. You also usually go this route since they will put up all the signage and all the alarms so the fire marshal won't flip the fuck out and everything is always up to code on that front.
The other option is rock the tanks yourself or run burners (i would avoid this). Again this route can be multi tanks throw together and a controller in each room. Generally you want to keep all the tanks in 1 spot for safety in case you have a regulator or a valve blow. Generally you want a controller in each room cause of different light cycles (if setup like that) and also since you will usually unplug the controller the last 2 weeks of flower unless all of your rooms are on the same schedule.