With my 5D2 I can hand hold the lens to 1/25th second in flourescent lighting that requires F2.8 at ISO 3200 with -1 stop exposure adjustment.
1/25s, f/2.8, ISO3200 = 2.6 LV
If you have to use -1 EVcomp in camera to get the exposure you want, that means that you are getting the camera to expose shorter (considering just the variation of shutter speed) than its metering wants too, and that otherwise the camera would treat it as a 1.6 LV exposure.
If instead you apply -1 EV in post processing in your raw processor and no EVcomp in camera, that means that you think that the 2.6 LV exposure that the camera chose is too long and, in your opinion, the metering should have treated the scene as a 3.6 LV exposure.
A Light Value calculator can be found here: