Backward chaining is invaluable to someone that can't get it naturally or has been taught bad mechanics or developed bad habits. Some kids have both ....doesn't come naturally and they have been taught wrong. Breaking it down into manageable pieces and backward chaining is a great way to break bad habits and make progress. Just doing full motion doesn't change anything so your practicing the same bad habits over and over, what is the definition of insane? Doing the same thing over and over, expecting a different result.