Yes.
My fastest commute times have been with Sid the Singlespeed. If I use a geared bike I'm generally slower. However when it's late at night, and I'm tired and knackered, it's so much nicer to be able to use gears on the way home.
Similarly with rides like the FNRttCs, I can do them on Sid, but with the Brighton run, when I hit Ditchling at 7am, I cannot be arsed to kill myself cycling all the way up. With gears I just change down and twiddle, rather than cough up my guts.