But that's the whole point of LC grinding: to claw your way through enough of these problems until, lo and behold... there ends up being an 80 percent chance that any given "medium" problem thrown at you -- is one that you have in fact seen and worked on, already.

I'm just guessing at the 80 percent figure. But it seems pretty clear from the cult of LC grinding that one of the goals of this strategy is not just to learn general techniques for solving these problems -- but to get a significantly high percentage of these problems under your belt already, or nearly so.

While also learning to deploy the just the right grunts and moans and pauses to make your interviewer think you're seeing the problem for the first time, of course.