Wingswinger, Very good point re its useless if you need 40% on the remaining engine to get the old girl going. I fly a Boeing and a way we do it is to shut down the #2 engine BUT
1) Start APU. Instead of leaving the #1 bleed ON, open the isolation valve and CLOSE the engine bleeds.
By using the APU for air the live engine has a lot more residual thrust and very rarely one needs to apply thrust to the live engine to maintain adequate speed.
L Met