NORMAL operations is all about fuel, whether the aircraft has 1,2,3,4, or 67 engines, sufficient fuel must be carried to provide for normal flight to a suitable airport from any point en-route with normal reserves, and in the 2 usually nominated non-normal conditions of depressurisation or engine failure, to provide for flight to a suitable airport from any point en-route with reserves applicable to that condition (In this context, Suitable, Acceptable, and Adequate airports are merged to the one word - Suitable).
Normal operations for 2 engined Transport category aircraft are limited to a maximum of 60 minutes flight time from a Suitable airport in the 1 engine inoperative condition. If the aircraft has PROVEN back-up systems (Hydraulics, electrical supply etc), AND the In-Flight Shut-Down (IFSD) rate is statistically low and acceptable to the certifying authority, then the aircraft / operator MAY be approved for ETOPS operations.
I regularly operate ETOPS flights from Singapore to the U.K., and the ETOPS critical sector is a mere One and a half hours out of Singapore crossing the Bay of Bengal. At that point, if suffering an engine failure, I have about 12 hours of fuel remaining to cover a 2 hour flight to the ETOPS contingency airport. Fuel is definately NOT a factor for ETOPS.
Regards,
Old Smokey