Why most daily planning fails by 10am

Most daily plans don't fail because they're wrong. They fail because the first interruption of the day gives you a legitimate-sounding reason to drop them.

The fix isn't a better plan. It's deciding, in advance, what you'll do when the plan gets interrupted -- because it always does.

That's the whole idea behind the Focusing Question in Chapter 1: one sentence you can return to after every interruption, so the day has a spine even when the schedule doesn't survive contact with reality.