When one exhaust fan is responsible for exhausting air in multiple rooms, should a switch be installed in each room?

You can do this. But the pressure of ordinary ventilation fans is not enough to exhaust the air this far. You'd better install a duct fan on the main pipe, and the air volume is the total flow. Pressure is the total loss of the air duct, you can calculate it. This means that the pressure loss in the main pipe is compensated by the duct fan, and the exhaust effect of your ventilation fans will be very good. Should be called together. Yes, but you need to make a deflector (or one-way door) between each exhaust fan and the main duct to prevent the airflow from flowing back into the room where the exhaust fan is not turned on.

If the pipes you add extend horizontally and the air outlets are at the same height, then you need to install a grid-type automatic door at the air outlet to prevent rainwater from pouring back during strong winds and heavy rains. However, this increases the wind resistance, and the wind pressure of the indoor exhaust fan is often not enough to open the damper and grille, resulting in poor exhaust. There are two solutions at this point.

First, raise the air outlet so that the air outlet is vertically upward, and use the buoyancy (pull force) generated by the difference in volumetric density of the air to discharge the indoor exhaust gas. And install a rainproof cover at the top of the air outlet one pipe diameter away from the air outlet to prevent rain