Depending on your hardware specs and processing power, bigger projects all on one drawing can start to slow down.
If your project is larger (over 500 devices in modelspace) you can start a project into multiple drawings (usually by floor) if necessary.
The circuit palette always shows all circuits from all panels no matter what drawing they are on, so circuits can be connected from one drawing to the next without any extra steps.
You will only need to override the length for connections between drawings, as a measurement and wirepath can't be drawn between separate files.
