Tuesday is the most productive workday
— By Tyler Falk on December 17, 2013, 1:45 PM PST
I'm surprised you didn't bring in research like the Hawthorne Effect, now largely rubbished. See BBC World Services excellent More or Less.
The methodology for the survey you are highlighting, does not really stand up to any challenge - Asking HR Managers "In your opinion, on which day of the week are employees generally most productive? is pretty subjective. I doubt many HR managers would not have any real clue, as that is a closer and better opinion of line managers in a direct report chain of the people doing the actual work. My HR manager is about 4 or 5 people removed from me and my team, and would not have the foggiest idea.
I agree, HR in general seems to be lost when they are asked about things under their own purvue. It would seem a fair bet that they really aren't aware of how or when real work gets done. Even managers can sometimes be out of he loop, HR managers would be even worse off.