Modern consoles don't behave like that, the tones can be simultaneously sent over multiple resources (by one person), and those resources can be multi-selected by the dispatcher and he or she can transmit the message over all of them at the same time. Derby and Ansonia are a perfect example, with the amount of mutual aid they do together, it doesn't make sense to dispatch one, and then the other to the same incident when one person could do both at the same time.
It also doesn't make sense that whenever there is a fire in the valley, every single responding department stays on their own channel and establishes their own incident command no matter where the fire is or who the actual incident commander is. "Unified command?" whats that?