Is it a usual practice from piano concertists to remove the specific hand far from the keyboard when this hand does not currently play for a certain duration, instead of keeping the hand just "above" the keyboard ?
Is is a recommendation from their teachers and/or schools ? Is it for artistic reasons or for "making some buzz" ? What is the goal ?
See this example :until 00:25, Valentina very oftens removes completely the left hand from the keyboard when the left hand does not play, while she could also have kept it "above" the keyboard, at the position of either the last key or the next key.