[cimmanom]

20-40 seconds? That's not enough time for a full context switch.

Take an eye break (look at something more than 20 feet away). Stand and stretch your back. Do a few desk-friendly stretches or exercises (curls, squats). Go to the kitchen for a beverage refill.

Somewhere around the 5 min mark for a wait it becomes time to check email, etc.

[bvrlt]

It's not enough for a full context switch but if you start opening your email, you might stay there longer than the 20-40 seconds and become a full context switch.

Eye break is a great idea.

[cimmanom]

Exactly