So buy in bulk if it's cheaper then per unit and buy per unit if it's cheaper than in bulk? Truly a brilliant advice. What's next? "Get multiple quotes and pick the best one"?
I'm sure we've all had an experience at least once where we've bought something in a larger container from the grocery store thinking we were getting a deal, only to find that we didn't get through it as fast as we thought we would, it started spoiling, and we got to scrape our savings into the trash can.
And many of us have had an experience where someone higher up in the company has insisted that we use a tool that isn't very good "because we've already paid for it", so it's clearly needed advice, even if it's not groundbreaking. Everyone sometimes needs "obvious" conclusions pointed out to them, I think. It's a quirk of our mental processing as humans.
Dressing up an obvious idea with fancy-sounding math formulas and pages of text is exactly how you get trapped by someone good at selling stuff.