“Many people do not believe that it takes a person 10 seconds to switch contexts; the time is measured between the final command executed in the previous context and the first command issued in the new context. The hiatus is not noticed because the minds of the users are occupied; they are not aware of the passage of time. However, this phenomenon should be used carefully when designing an interface. If the work flow is such that a user makes a particular context switch repeatedly, so that it becomes habitual, the user makes the switch in far less time. – Jef Raskin, The Humane Interface

Context switches add up over the course of a day…