Try this: after listening to a story or to a lecture, retell it to someone else in as much detail as possible. Or try defending lecturer's position or what their information implies. You'll be shocked to discover, you don't know enough details.

You'll have to listen another time, and off goes the profit of x2 speed. But even after listening multiple times, it's still very hard to argue for, or retell in details what's been said. Unless it's a radio show, where information is sparse.