3 part fuel induction service. How often does this need to be serviced?

It never needs done. It is a "value added" service offered by repair facilities that does very little to your 2012 Ridgeline. Cleaning the combustion chamber and fuel system is what is claimed, but with the detergents already present in your gasoline, we do not experience anything that would require such a cleaning typically. I would recommend spending the money on something more valuable.

Unless you are experiencing fuel related engine performance problems - - Absolutely unnecessary!