I think this varies on the photographer and the event. The best wedding photographer I know doesn't spend much time post-processing...he gets it right in the field. However, he's also a photojournalistic-style shooter, and doesn't do any Photoshop effects.

My style is similar, but I'm not as good as him The last wedding I shot, I think I took 800 photos over 10 hours (I was the second-shooter, so I didn't do many portraits...mostly candids). From that, I narrowed it down to about 250 or so. Color correction (freaking church was incredibly orange), exposure adjustments, and minor tweaking (vibrance, spot touches, etc) all took me about 5 hours or so. Again, no photoshop effects except for a little vignetting on a few photos.

15/min per photo seems like a lot. If I have to spend that long on a photo, I usually toss it.