@Naughtok - as @Gene pointed out there are some electrical component limitations in the Rachio. Then, I think the wire gauge and distance out to the solenoids along with the individual actual solenoid power draw come into play. If the installation doesn’t have a master valve or pump start relay installed one could attempt three wires in one terminal. If so, I’d send a request to Rachio support after it has run to see what the current load is and how close that is to the limit for a single zone. If there is only one zone that needs three solenoids running at once, and the master valve and pump start relay aren’t used, I’d split the load between the zone and the MV terminals using a 24 VAC SPST NO relay to power two of the zones. In this set up the zone terminal would power one solenoid and the relay coil and the MV terminal would be connected through the throw on the relay to the two other solenoids.
