Back when I was in engineering, there was a story told about one of the profs:

He would say ‘Memorize! No time to derive!’, meaning that in order to do the questions on the exam quickly enough, you would have to memorize the formulae in their applicable form, instead of deriving them from first principles each time.

For me, there is a clear analogy to the regular brain remapping you do everyday through your choices of what to do and think about.

There’s also a clear analogy to performance, whether that is singing, dancing, or powerpoint. It’s important to know your ‘words and notes’ off by heart, backwards and forwards, so that you can focus on the task at hand, whether it’s entertaining people, conveying a message[1], or solving a problem.

[1]These are often one and the same.