Planning and executing can’t be done at the same time, and it is surprisingly difficult to jump from one to the other when it would benefit to do so. Planning and execution are not equivalent tasks in difficulty or value. There are far fewer people who can plan than there are those who can execute. There are fewer still who can do both, as this requires not just the presence of two highly independent skills, but the rare ability to move between them at the appropriate time. This is the most difficult skill of the three, since it takes something special to be able to sense when the switch is needed without detracting from the whole focus needed to design or execute well.