If you can control the lighting and need to make sure each shot is lit and exposed perfectly then tools like that are wonderful. I've never used that particular one, but I used calibration targets
like these when I ran a district for one of the big school photo yearbook companies. I would train my photographers to set up four lights according to diagram then use the white side of the target to take a custom white balance. Then flip and shoot the black/grey/white side, adjusting exposure until the histogram had three spikes all within range. We set the cameras up exactly the way we wanted them and shot JPGs, so we never had to process a single image before we sent it to the printer unless someone goofed.
Today I don't even bother. Today's DSLR cameras seem to do pretty well on auto when I'm shooting available light and I can check it in the LCD screen and make fine adjustments. 90% of the time I'm mixing strobe with available light, bouncing it around and/or shooting on the run and taking test shots is quicker. It just depends on the situation and lighting.
What I guess I would really like to have some day is a color meter and a huge book of gel swatches. I'd take an available light temperature reading then gel my flash to match then shoot a custom white balance of it all. This would be great for using flash to fill indoors.
When I did newspaper work and we were shooting film, I would carry a few different green gels for florescent lights and a few amber gels for incandescent. I'd eyeball it and usually it was close enough.
All this talk of shooting raw and then spending hours in post processing makes me tired, but I'm pretty much naturally lazy. My goal is to get every shot right in camera and save myself time and money. It didn't mater too much when I was shooting news since photoshopping half a dozen images isn't too much work. When I shoot Santa photos at the mall or a wedding and I need each one of hundreds to be printable then I do my best to get it right in camera using every trick I know.