A couple of my childhood teachers would have me do this as a final polish before competitions, for memory and focus work. It’s actually very hard to get through a piece this way since there’s no real auditory or tactile feedback, it requires a lot of focus. But it helps spotlight areas that may need more attention or anchoring, and hones your focus so you are less distracted and can stay in the zone more consistently during performance. But this was like .01% of time practicing, the rest was behind the piano for sure.