After hearing this story for years and finally trying to source it, as far as I can tell it's not entirely clear this experiment was ever actually run -- and in

After hearing this story for years and finally trying to source it, as far as I can tell it's not entirely clear this experiment was ever actually run -- and in fact is sourced in the link behind your link as a "parable." I can imagine it's true that churning out quantity is its own education but I can also imagine there's a plateau past which deliberate practice and polish matter quite a bit.