"Learning meta-rules is more difficult and time-consuming than learning procedural rules... Ontogenetically, social meta-learning follows the learning of procedural rules. This is comparable to the acquisition of language and memory use. Children first acquire examples of grammatically correct language (likeliked; stand-stood), then recognise the rules (if you need past tense, add -ed to the infinitive form) and go through a phase where they make 'errors' that they did not make before (stand-standed). Finally, they learn exceptions to the rule and rules governing exceptions."
"Machiavellian Intelligence II: Extensions and Evaluations", Whiten & Byrne.
This is why we keep our code refactored nicely.