I think that you'll find that depends on the camera and the settings you use. I have my Panasonic G2s set up to preview mode, so what I see is what I keep. On the Sony R1, the EVF is so primitive that I just have to guess in poor light. Or I can switch over to the main LCD, which I normally use as a waist level finder and, once again, see what the final image will look like.
This shot was made at dusk on the R1, using the main LCD as a waist level finder...