fyi.. I’ve been using Bruce Fraser’s method since before it was published (2004). In my view it’s a kludgy poor man’s calibration, and not repeatable. Try it. Hide the results from the first go-round. Then do it again. Then do it again. If you get the same results within 2% (Lab numbers in the calibrated file), you have a color god in your favor. Bruce F. was an expert and did this for a living. The typical user simply wants good color management without making a career of it.
That was one of the reasons I went to Capture One, then RSP. Use of camera profiles for various conditions. Way cool.
btw... I'm trying to build a spread sheet that converts 8-bit RGB values (Adobe 1998 or ProPhoto) to Lightroom style "Melissa RGB" expressed in percentages. If anyone out there has done this, please share. fyi.. per A. Rodney: "For this reason, the histogram and numeric values provided in Lightroom are based on ProPhoto RGB, using the sRGB Tone Response Curve (primarily based on a 2.2 gamma with a tweak to the tone curve in the shadows)."
I believe Photoshop's native space is Lab, Lightroom not. And so it goes..
enjoy, photography is so much fun!
p