I know I prefer to practice my "incorrect" movements at full speed; we get thru them much more quickly that way
Not sure I understand the problem some have with "matrixing" a swing, though. I wouldn't say we use it often; but I do think slowing the process down to focus on a particular point of emphasis has real value. Maybe I'm performing it incorrectly
As I understand it (I could be wrong), it's because some people do not believe the swing should be taught as a series of positions, but rather movements.