The new twins collect telemetry data from the entire flight. Maintenance is scheduled based on cumulative stresses on the engine and not on miles flown.

They end up going longer between service windows (reduced labor) but it also means they’re more of a known quantity and shouldn’t fall off over the Atlantic. And as we’ve discussed many times in SpaceX threads, having more moving parts may increase the likelihood of a failure instead of reducing it.

So you have bigger engines, more efficient airframes, fewer moving parts, and better maintenance records, why not fly them over the ocean with only two engines?