[MikeTheGreat]

I'd be interested to know if this is true generally, or just for people learning a new skill.

I.e., Making a lot of pottery without caring about the individual quality leads to more learning (possibly because you can try lots of new stuff without fear of failure, possibly because when you find something that works you can keep practicing it, etc, etc).

Once you know what you're doing I can't imagine that blasting through something in a half-assed fashion produces better results than carefully doing a thoughtful job.

[ThrustVectoring]

Definitely the latter, sorry if the story wasn't clear about that. Spending more time on an individual piece means that within the band of results your current skill is capable of delivering, you get a better result. Repetition, on the other hand, does a much better job of improving your skill.