I always wonder what percentage of corporate America's time is spent looking busy or alt-tabbing between a spreadsheet and solitaire when the boss walks by. If you could quantify it I bet the amount of waste is staggering.
Fortunately I've only ever worked one place where that was super-useful, and only briefly. Got three novels read while also completing my work and doing a bunch of other work that I probably didn't need to, in ~2 months' time.
It's employees who get screwed by this - if their managers are too concerned about waste, they can't do anything like read a book or go for a walk, so they're on Facebook and Reddit, which are much less effective as breaks from focused work.