Steve racks up more hours then you'd ever dream of, and his boat is untrailerable and spends most of it's time in the water so on water maintenance is not uncommon. The servicing schedule for plugs is every 400 hours, he's racked up over 4000 hence the plug changes.
An Etec as advertised has a scheduled service of either after 3 years or 300 hours. You obviously haven't racked up 300 hrs yet as the plugs would usually be one of the first things I'm sure the technician would be pulling out and checking.![]()