relative difficulty of planning vs implementing

[ArcCaster]

David says that he creates task lists that are so detailed that they can be executed even by somebody oxygen-deprived and sleep-deprived.

And of course, when we execute our task lists, we are generally in a better state than that.

So, can I conclude that executing a task requires a fraction of the brainpower that planning does? And vice versa, that planning is an order of magnitude more difficult than executing?

And if so, I better save my best hours for planning? (Currently, I have my calendar marked 'weekly review' every Thursday at 4:00 PM, figuring I will have done a lot of useful work by then, and can kick back and do the more mechanical weekly review that doesn't require a lot of energy -- but I am wondering if I have scheduled it for exactly the opposite of what I should)