The eheims, in my scenario, are not switching. The apex, or other supervisory controller is switching.
Eheims set 2 degres above apex, so no switching, just a thermal safety.
It means that the bimetal contacts more or less always will be in contact mode. I´m not sure you will hinder the "welding" process in that case. My experiences - even with Jaeger and Eheim heaters (they are the same nowadays) they will broke sooner or later - and mostly in on mode. But that´s my opinion based on my own experience - I am not using any heater with internal control nowadays. And in saltwater - I always use Titan heaters - they are grounded and I am very much against using high voltage AC equipment in saltwater if they not are properly grounded.