If the answer were easy, management consultants wouldn't be thriving . So spare a moment for "The Shock of the New Chic," the 2014 luxury report from Boston Consulting Group.

As Jean-Marc Bellaiche, head of BCG's Luxury, Fashion and Beauty practice, narrated a PowerPoint presentation about the report, he mentioned that watches are often one of the first purchases of the "newly affluent." They last longer than other luxury purchases (a safari, say), offering the biggest bang for your buck over time.

Seems like a logical approach to an irrational decision-making process. Let's ask what many companies wish they had asked before hiring consultants. Does it work?

Let's see. A good suit is supposed to last forever, but tastes and waists change, so say you have it for 10 years. Over those 10 years, you'll probably wear it once a week on average -- though if it's a winter suit you probably won't wear it in the summer, and vice versa. At best you'll get 520 days out of the suit, meaning it will cost you $2.31 per wear.

Now for the watch . You can wear a watch every day, but let's say you leave it at home on the weekends -- that's still 2,600 wears over a 10-year period, which comes to $1.34 per wear, or 42 percent less than the suit.

Of course, a good suit, unlike a fancy watch, is essential. Still, BCG has a point. Is the watch really three times as expensive as the suit, in the long run? Do the math. Weigh the relative values. Conduct a regression analysis. Or fire the consultants and just check your bank account.

Before it's here, it's on the Bloomberg Terminal. LEARN MORE