good question mate. I always take a spinning setup incase i come across a school of tuna or macks, then a flick stick for SP. A bait rod incase and always have a big gun in the boat for trolling. So 4 I guess.
Have been caught out couple times but. Have 3 rods down and they all go off at once! Good to be prepared for anything but i reckon. Save changing rigs out on the water.