Focus On Doing One Thing

Multitasking feels efficient and measures badly. What it mostly produces is fatigue and a day with nothing finished.

Doing several things at once feels productive. That feeling is the problem, because it is generated by the activity rather than by the output.
You are not doing two things, you are switching
The brain does not run two demanding tasks in parallel. It alternates, and every alternation carries a cost. A fragment of the previous task stays active while you begin the next, so you start each one slightly degraded.
With small tasks the cost is small. With anything requiring real thought it is substantial, and it is invisible, which is why people keep paying it.
The tiredness is real and it is disproportionate
A day of constant switching leaves people more exhausted than a day of sustained difficult work, while producing considerably less. That combination is what burns people out, and they usually blame the volume rather than the fragmentation.
Boredom is the reason we do it
Worth being honest about. Single-tasking is often less interesting. The switch to the inbox is not efficiency, it is relief from the discomfort of one thing for a long time.
Which means the fix is partly about tolerating a mild unpleasantness rather than installing a system.
What actually helps
Blocks, with a defined start and end. One task per block, chosen in advance so no decision is required at the time. The other tasks visible on a list, because most switching is driven by the fear of forgetting something.
Notifications off for the duration. Not minimised. Off.
The measure to trust
Not how full the day felt. What is finished at the end of it. Those two diverge sharply, and only one of them is worth anything the following morning.

















