The real cost of context-switching (it's not the 20 minutes)

You've probably heard the '23 minutes to refocus' number. It's a real study, and it's directionally true -- but it's not the cost that actually wrecks a day.

The bigger cost is that context-switching quietly changes what you consider a reasonable next move. After the fourth switch, opening one more tab feels free. It isn't.

Chapter 4 covers a narrower fix than 'block your calendar': naming the switch out loud, every time, before you take it. It sounds small. It isn't.