I'm also curious if others use the print adjustment setting to "calibrate" their printer.
I have two answers...one snarky and the other practical;
Snarky: Alain has only just recently decided that printing from Lightroom makes really good sense for a variety of reasons and so has fallen into the trap of taking an easy way out of a typical problem (even experienced by a long time printer like Alain) of predicting what an image on screen will look like on paper. Note that Alain hasn't talked much about soft proofing (which I know he at least knows about because he's seen my lectures on soft proofing) because I'm not sure he does soft proof "correctly"...so unfortunately Alain is advising use of a tool that should not be needed...(sorry Alain)
Practical: do whatever you need to do to get the final print you want and demand and if that means doing the wrong technical thing but achieves the correct result, then do what it takes.
Sadly, I won't be seeing Alain till next year so that I can sit him down and make him write "I Will Not Use The Print Adjustment Function Again" a hundred times and reconstruct him why you don't want to do that and how soft proofing solves the print is too dark problem as well as control over tone mapping and color rendering.
I soft proof every serious print I make because I want it to look as good as it can be. I don't use the Print Adjustment tool...I don't need to.