I believe ETOPS was developed to help make the 767 a viable twin-engine option for long flights over water (ETOPS-120). That subsequently led to ETOPS-180 etc.

I believe ETOPS was developed to help make the 767 a viable twin-engine option for long flights over water (ETOPS-120). That subsequently led to ETOPS-180 etc. Now there's ETOPS-330! ETOPS-N: N number of minutes over open water, roughly, I think.