Microburst2002
Yes the gains easily overcome the windmilling drag. Of course we had 4 spey 250s embedded in the wing roots. Once we started flying around at 1000' agl or below 4 engines were way too many. We could almost always shut one down straight away. As the weight reduced we would bring the second back to idle firstly. And only when we had a certain amount of single engine performance (we're talking a 4 jet here) would we actually shut down the second engine. Now if we happened to have a problem with one of the two remaining engines the first action was to relight one of the shutdown ones.
Next time you have your holding tables in front of you compare two engine fuel flow when holding at 1500' at typical landing weights with single engine holding at the same weight. You may be surprised.
Many ETOPS critical fuel scenarios are decompression with 2 engines running rather than decompression with engine failure.