I made an adage some years ago:

Practice doesn't necessarily make perfect, it can also make you habitually wrong.

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I've trained, I don't, 50 apprentices. They all learn faster of they can do a short stint on a new task, say 10 to 29 mins, then come back to it after at least one sleep.

They almost always develop bad habits if you make then do the new task all day because they'll get either overly focused on some inconsequential aspect of it, it lose interest because they're not good at it, or sone such.