As for the rest of us, who spend the last few hours of the workweek struggling to read an email without zoning out, there's a much more efficient way you could be using this time.
Instead of forcing yourself to focus when you're feeling mentally depleted, plan for the week ahead. That's the simple but likely underutilized tip from Laura Vanderkam, author of multiple books on time-management and productivity, including most recently, "I Know How She Does It."
Specifically, you'll want to make a three-category priority list, with slots for work, relationships, and self.
"We tend not to be doing a whole lot else on Friday afternoon," Vanderkam said when she visited the Business Insider office in October. (It's worth noting here that Vanderkam has analyzed dozens of time logs from high-earning women.)
"We're sort of cruising toward the weekend anyway in our minds, but we haven't left work yet."
So why the three buckets?
"It then reminds us that there should be something in all three categories," Vanderkam said. "It's easy to think about work. Relationships or self, not so much."
Vanderkam recommends putting two to three items in each category, then looking over your calendar for the following week, and seeing where you can fit them in.
"That way, you make sure that the important stuff happens."
Of course, there's no guarantee that work demands won't get in the way of your planned gym classes or date nights. But if you leave these relationship and self priorities off your calendar entirely, there's basically zero chance you'll attend to them.
Another way to use Friday afternoons: Do a "calendar triage."
Vanderkam suggests looking at what's already on your calendar and asking yourself what you really don't want to do. If you're going to cancel the plans, she said, it's better to do it now than five minutes beforehand.
Identify activities that can be minimized - namely, long meetings - and tasks that you can delegate to a coworker.
By taking just a few minutes to plan, Vanderkam said, "you can literally buy yourself hours that you can then devote to more important things."