To drill into your example more, I think that many small issues in proficiency get carried on through schooling, especially in areas like mathematics. My little

To drill into your example more, I think that many small issues in proficiency get carried on through schooling, especially in areas like mathematics. My little sister-in-law was having trouble with it at school, and started doing some Kumon method remedial classes. http://en.wikipedia.org/wiki/Kumon_method http://en.wikipedia.org/wiki/Kumon_method The material was embarrassingly simple for her, but speed and accuracy improvements at this simple level suddenly made the more difficult mathematics her peers were studying accessible, and her ability picked up substantially. I'd say this is an example, not so much of practicing doing it wrong, but of practicing the wrong thing for her level. Given that skills build on on another, plenty of people might be practicing later skills poorly, instead of the base skills they really need to progress.